ff-encode 0.14.1

//! Codec option application and encoder selection helpers.
#![allow(unsafe_op_in_unsafe_fn)]
#![allow(clippy::ptr_as_ptr)]
#![allow(clippy::cast_possible_wrap)]

use super::{
    AVCodecContext, AVCodecID, AVCodecID_AV_CODEC_ID_AAC, AVCodecID_AV_CODEC_ID_AC3,
    AVCodecID_AV_CODEC_ID_ALAC, AVCodecID_AV_CODEC_ID_AV1, AVCodecID_AV_CODEC_ID_DNXHD,
    AVCodecID_AV_CODEC_ID_DTS, AVCodecID_AV_CODEC_ID_EAC3, AVCodecID_AV_CODEC_ID_FFV1,
    AVCodecID_AV_CODEC_ID_FLAC, AVCodecID_AV_CODEC_ID_H264, AVCodecID_AV_CODEC_ID_HEVC,
    AVCodecID_AV_CODEC_ID_MJPEG, AVCodecID_AV_CODEC_ID_MP3, AVCodecID_AV_CODEC_ID_MPEG2VIDEO,
    AVCodecID_AV_CODEC_ID_MPEG4, AVCodecID_AV_CODEC_ID_NONE, AVCodecID_AV_CODEC_ID_OPUS,
    AVCodecID_AV_CODEC_ID_PCM_S16LE, AVCodecID_AV_CODEC_ID_PCM_S24LE, AVCodecID_AV_CODEC_ID_PNG,
    AVCodecID_AV_CODEC_ID_PRORES, AVCodecID_AV_CODEC_ID_VORBIS, AVCodecID_AV_CODEC_ID_VP8,
    AVCodecID_AV_CODEC_ID_VP9, AudioCodec, CString, EncodeError, VideoCodec, VideoEncoderInner,
    avcodec,
};

/// Convert VideoCodec to FFmpeg AVCodecID.
pub(super) fn codec_to_id(codec: VideoCodec) -> AVCodecID {
    match codec {
        VideoCodec::H264 => AVCodecID_AV_CODEC_ID_H264,
        VideoCodec::H265 => AVCodecID_AV_CODEC_ID_HEVC,
        VideoCodec::Vp9 => AVCodecID_AV_CODEC_ID_VP9,
        VideoCodec::Av1 => AVCodecID_AV_CODEC_ID_AV1,
        VideoCodec::Av1Svt => AVCodecID_AV_CODEC_ID_AV1,
        VideoCodec::ProRes => AVCodecID_AV_CODEC_ID_PRORES,
        VideoCodec::DnxHd => AVCodecID_AV_CODEC_ID_DNXHD,
        VideoCodec::Mpeg4 => AVCodecID_AV_CODEC_ID_MPEG4,
        VideoCodec::Vp8 => AVCodecID_AV_CODEC_ID_VP8,
        VideoCodec::Mpeg2 => AVCodecID_AV_CODEC_ID_MPEG2VIDEO,
        VideoCodec::Mjpeg => AVCodecID_AV_CODEC_ID_MJPEG,
        VideoCodec::Png => AVCodecID_AV_CODEC_ID_PNG,
        VideoCodec::Ffv1 => AVCodecID_AV_CODEC_ID_FFV1,
        _ => AVCodecID_AV_CODEC_ID_NONE,
    }
}

pub fn preset_to_string(preset: &crate::Preset) -> String {
    match preset {
        crate::Preset::Ultrafast => "ultrafast",
        crate::Preset::Faster => "faster",
        crate::Preset::Fast => "fast",
        crate::Preset::Medium => "medium",
        crate::Preset::Slow => "slow",
        crate::Preset::Slower => "slower",
        crate::Preset::Veryslow => "veryslow",
    }
    .to_string()
}

/// Convert AudioCodec to FFmpeg AVCodecID.
pub(super) fn audio_codec_to_id(codec: AudioCodec) -> AVCodecID {
    match codec {
        AudioCodec::Aac => AVCodecID_AV_CODEC_ID_AAC,
        AudioCodec::Opus => AVCodecID_AV_CODEC_ID_OPUS,
        AudioCodec::Mp3 => AVCodecID_AV_CODEC_ID_MP3,
        AudioCodec::Flac => AVCodecID_AV_CODEC_ID_FLAC,
        AudioCodec::Pcm => AVCodecID_AV_CODEC_ID_PCM_S16LE,
        AudioCodec::Pcm16 => AVCodecID_AV_CODEC_ID_PCM_S16LE,
        AudioCodec::Pcm24 => AVCodecID_AV_CODEC_ID_PCM_S24LE,
        AudioCodec::Vorbis => AVCodecID_AV_CODEC_ID_VORBIS,
        AudioCodec::Ac3 => AVCodecID_AV_CODEC_ID_AC3,
        AudioCodec::Eac3 => AVCodecID_AV_CODEC_ID_EAC3,
        AudioCodec::Dts => AVCodecID_AV_CODEC_ID_DTS,
        AudioCodec::Alac => AVCodecID_AV_CODEC_ID_ALAC,
        _ => AVCodecID_AV_CODEC_ID_NONE,
    }
}

impl VideoEncoderInner {
    /// Apply per-codec options to an allocated (not yet opened) codec context.
    ///
    /// All `av_opt_set` return values are checked; a negative value is logged
    /// as a warning and skipped — it never propagates as an error.
    ///
    /// # Safety
    ///
    /// `codec_ctx` must be a valid non-null pointer to an allocated
    /// `AVCodecContext` whose `priv_data` has been set by
    /// `avcodec_alloc_context3`. Must be called **before** `avcodec_open2`.
    pub(super) unsafe fn apply_codec_options(
        codec_ctx: *mut AVCodecContext,
        opts: &crate::video::codec_options::VideoCodecOptions,
        encoder_name: &str,
    ) {
        use crate::video::codec_options::VideoCodecOptions;
        use std::ffi::CString;

        match opts {
            VideoCodecOptions::H264(h264) => {
                // profile
                if let Ok(s) = CString::new(h264.profile.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null (set by avcodec_alloc_context3);
                    // option name and value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"profile\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=profile value={} encoder={encoder_name}",
                            h264.profile.as_str()
                        );
                    }
                }
                // level (only when explicitly set)
                if let Some(level) = h264.level {
                    let level_str = level.to_string();
                    if let Ok(s) = CString::new(level_str.as_str()) {
                        // SAFETY: codec_ctx and priv_data are non-null; option name and
                        // value are valid NUL-terminated C strings.
                        let ret = ff_sys::av_opt_set(
                            (*codec_ctx).priv_data,
                            b"level\0".as_ptr() as *const i8,
                            s.as_ptr(),
                            0,
                        );
                        if ret < 0 {
                            log::warn!(
                                "av_opt_set failed option=level value={level} \
                                 encoder={encoder_name}"
                            );
                        }
                    }
                }
                // Direct codec context fields.
                // SAFETY: codec_ctx is a valid allocated AVCodecContext.
                (*codec_ctx).max_b_frames = h264.bframes as i32;
                (*codec_ctx).gop_size = h264.gop_size as i32;
                (*codec_ctx).refs = h264.refs as i32;
                // preset (libx264-specific; hardware encoders return a negative value
                // which we log and skip — never returned as an error)
                if let Some(preset) = h264.preset
                    && let Ok(s) = CString::new(preset.as_str())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; option name
                    // and value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"preset\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=preset value={} \
                             encoder={encoder_name}",
                            preset.as_str()
                        );
                    }
                }
                // tune (libx264-specific; hardware encoders return a negative value
                // which we log and skip — never returned as an error)
                if let Some(tune) = h264.tune
                    && let Ok(s) = CString::new(tune.as_str())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; option name
                    // and value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tune\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tune value={} \
                             encoder={encoder_name}",
                            tune.as_str()
                        );
                    }
                }
            }
            VideoCodecOptions::H265(h265) => {
                // profile
                if let Ok(s) = CString::new(h265.profile.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"profile\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=profile value={} encoder={encoder_name}",
                            h265.profile.as_str()
                        );
                    }
                }
                // Auto-select yuv420p10le for Main10 (may be overridden by an explicit
                // pixel_format() call applied after apply_codec_options returns).
                if h265.profile == crate::video::codec_options::H265Profile::Main10 {
                    // SAFETY: codec_ctx is valid; direct field write is safe.
                    (*codec_ctx).pix_fmt = ff_sys::AVPixelFormat_AV_PIX_FMT_YUV420P10LE;
                }
                // tier
                if let Ok(s) = CString::new(h265.tier.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tier\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tier value={} encoder={encoder_name}",
                            h265.tier.as_str()
                        );
                    }
                }
                // level (only when explicitly set)
                if let Some(level) = h265.level {
                    let level_str = level.to_string();
                    if let Ok(s) = CString::new(level_str.as_str()) {
                        // SAFETY: codec_ctx and priv_data are non-null; option name and
                        // value are valid NUL-terminated C strings.
                        let ret = ff_sys::av_opt_set(
                            (*codec_ctx).priv_data,
                            b"level\0".as_ptr() as *const i8,
                            s.as_ptr(),
                            0,
                        );
                        if ret < 0 {
                            log::warn!(
                                "av_opt_set failed option=level value={level} \
                                 encoder={encoder_name}"
                            );
                        }
                    }
                }
                // preset (libx265-specific; hardware HEVC encoders return a negative value
                // which we log and skip — never returned as an error)
                if let Some(ref preset) = h265.preset
                    && let Ok(s) = CString::new(preset.as_str())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; option name
                    // and value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"preset\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=preset value={preset} \
                             encoder={encoder_name}"
                        );
                    }
                }
                // x265-params raw passthrough (libx265 only)
                if let Some(ref params) = h265.x265_params
                    && let Ok(s) = CString::new(params.as_str())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; option name
                    // and value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"x265-params\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=x265-params value={params} \
                             encoder={encoder_name}"
                        );
                    }
                }
            }
            VideoCodecOptions::Av1(av1) => {
                // cpu-used
                let cpu_used_str = av1.cpu_used.to_string();
                if let Ok(s) = CString::new(cpu_used_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"cpu-used\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=cpu-used value={} encoder={encoder_name}",
                            av1.cpu_used
                        );
                    }
                }
                // tile-rows
                let tile_rows_str = av1.tile_rows.to_string();
                if let Ok(s) = CString::new(tile_rows_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile-rows\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile-rows value={} encoder={encoder_name}",
                            av1.tile_rows
                        );
                    }
                }
                // tile-columns
                let tile_cols_str = av1.tile_cols.to_string();
                if let Ok(s) = CString::new(tile_cols_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile-columns\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile-columns value={} \
                             encoder={encoder_name}",
                            av1.tile_cols
                        );
                    }
                }
                // usage
                if let Ok(s) = CString::new(av1.usage.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"usage\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=usage value={} encoder={encoder_name}",
                            av1.usage.as_str()
                        );
                    }
                }
            }
            VideoCodecOptions::Av1Svt(svt) => {
                // preset (0–13)
                let preset_str = svt.preset.to_string();
                if let Ok(s) = CString::new(preset_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"preset\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=preset value={} \
                             encoder={encoder_name}",
                            svt.preset
                        );
                    }
                }
                // tile-rows
                let tile_rows_str = svt.tile_rows.to_string();
                if let Ok(s) = CString::new(tile_rows_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile_rows\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile_rows value={} \
                             encoder={encoder_name}",
                            svt.tile_rows
                        );
                    }
                }
                // tile-columns
                let tile_cols_str = svt.tile_cols.to_string();
                if let Ok(s) = CString::new(tile_cols_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile_columns\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile_columns value={} \
                             encoder={encoder_name}",
                            svt.tile_cols
                        );
                    }
                }
                // svtav1-params raw passthrough
                if let Some(ref params) = svt.svtav1_params
                    && let Ok(s) = CString::new(params.as_str())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; option name and
                    // value are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"svtav1-params\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=svtav1-params value={params} \
                             encoder={encoder_name}"
                        );
                    }
                }
            }
            VideoCodecOptions::Vp9(vp9) => {
                // CQ mode: override bitrate to 0 and set crf
                if let Some(cq) = vp9.cq_level {
                    // SAFETY: codec_ctx is non-null; direct field write is safe.
                    (*codec_ctx).bit_rate = 0;
                    let cq_str = cq.to_string();
                    if let Ok(s) = CString::new(cq_str.as_str()) {
                        // SAFETY: codec_ctx and priv_data are non-null; strings are
                        // NUL-terminated.
                        let ret = ff_sys::av_opt_set(
                            (*codec_ctx).priv_data,
                            b"crf\0".as_ptr() as *const i8,
                            s.as_ptr(),
                            0,
                        );
                        if ret < 0 {
                            log::warn!(
                                "av_opt_set failed option=crf value={cq} \
                                 encoder={encoder_name}"
                            );
                        }
                    }
                }
                // cpu-used
                let cpu_used_str = vp9.cpu_used.to_string();
                if let Ok(s) = CString::new(cpu_used_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"cpu-used\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=cpu-used value={} \
                             encoder={encoder_name}",
                            vp9.cpu_used
                        );
                    }
                }
                // tile-columns
                let tile_cols_str = vp9.tile_columns.to_string();
                if let Ok(s) = CString::new(tile_cols_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile-columns\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile-columns value={} \
                             encoder={encoder_name}",
                            vp9.tile_columns
                        );
                    }
                }
                // tile-rows
                let tile_rows_str = vp9.tile_rows.to_string();
                if let Ok(s) = CString::new(tile_rows_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"tile-rows\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=tile-rows value={} \
                             encoder={encoder_name}",
                            vp9.tile_rows
                        );
                    }
                }
                // row-mt
                let row_mt_str = if vp9.row_mt { "1" } else { "0" };
                if let Ok(s) = CString::new(row_mt_str) {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"row-mt\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=row-mt value={row_mt_str} \
                             encoder={encoder_name}"
                        );
                    }
                }
            }
            VideoCodecOptions::ProRes(prores) => {
                // Set pixel format based on profile before avcodec_open2.
                // 4444 profiles need yuva444p10le; 422 profiles need yuv422p10le.
                // SAFETY: codec_ctx is non-null; direct field write is safe.
                if prores.profile.is_4444() {
                    (*codec_ctx).pix_fmt = ff_sys::AVPixelFormat_AV_PIX_FMT_YUVA444P10LE;
                } else {
                    (*codec_ctx).pix_fmt = ff_sys::AVPixelFormat_AV_PIX_FMT_YUV422P10LE;
                }

                // Apply profile via av_opt_set on priv_data.
                let profile_str = prores.profile.profile_id().to_string();
                if let Ok(s) = CString::new(profile_str.as_str()) {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"profile\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=profile value={} \
                             encoder={encoder_name}",
                            prores.profile.profile_id()
                        );
                    }
                }

                // Apply optional vendor tag.
                if let Some(vendor) = prores.vendor
                    && let Ok(s) = CString::new(vendor.as_ref())
                {
                    // SAFETY: codec_ctx and priv_data are non-null; strings are
                    // NUL-terminated.
                    let ret = ff_sys::av_opt_set(
                        (*codec_ctx).priv_data,
                        b"vendor\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        0,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=vendor \
                             encoder={encoder_name}"
                        );
                    }
                }
            }
            VideoCodecOptions::Dnxhd(dnxhd) => {
                use ff_format::PixelFormat;

                // Set pixel format based on variant before avcodec_open2.
                // SAFETY: codec_ctx is non-null; direct field write is safe.
                (*codec_ctx).pix_fmt = match dnxhd.variant.pixel_format() {
                    PixelFormat::Yuv422p => ff_sys::AVPixelFormat_AV_PIX_FMT_YUV422P,
                    PixelFormat::Yuv422p10le => ff_sys::AVPixelFormat_AV_PIX_FMT_YUV422P10LE,
                    PixelFormat::Yuv444p10le => ff_sys::AVPixelFormat_AV_PIX_FMT_YUV444P10LE,
                    _ => ff_sys::AVPixelFormat_AV_PIX_FMT_YUV422P,
                };

                // For DNxHD variants, override bit_rate with the required fixed rate.
                if let Some(bps) = dnxhd.variant.fixed_bitrate_bps() {
                    // SAFETY: codec_ctx is non-null; direct field write is safe.
                    (*codec_ctx).bit_rate = bps;
                }

                // Apply vprofile via av_opt_set on codec_ctx with AV_OPT_SEARCH_CHILDREN.
                // Using the codec context (not priv_data) with SEARCH_CHILDREN allows the
                // option to be found in child objects including priv_data.
                if let Ok(s) = CString::new(dnxhd.variant.vprofile_str()) {
                    // SAFETY: codec_ctx is non-null and cast to *mut c_void as required
                    // by av_opt_set. AV_OPT_SEARCH_CHILDREN (1) searches child objects.
                    // Strings are valid NUL-terminated C strings.
                    let ret = ff_sys::av_opt_set(
                        codec_ctx as *mut std::ffi::c_void,
                        b"vprofile\0".as_ptr() as *const i8,
                        s.as_ptr(),
                        ff_sys::AV_OPT_SEARCH_CHILDREN as i32,
                    );
                    if ret < 0 {
                        log::warn!(
                            "av_opt_set failed option=vprofile value={} \
                             encoder={encoder_name}",
                            dnxhd.variant.vprofile_str()
                        );
                    }
                }
            }
        }
    }

    /// Select best available video encoder for the given codec.
    ///
    /// This method implements LGPL-compliant codec selection with automatic fallback:
    /// - For H.264: Hardware encoders → libx264 (GPL only) → VP9 fallback
    /// - For H.265: Hardware encoders → libx265 (GPL only) → AV1 fallback
    /// - Hardware encoders (NVENC, QSV, AMF, VideoToolbox) are LGPL-compatible
    /// - VP9 and AV1 are LGPL-compatible
    pub(super) fn select_video_encoder(
        &self,
        codec: VideoCodec,
        hardware_encoder: crate::HardwareEncoder,
    ) -> Result<String, EncodeError> {
        // Early check: when Av1Svt is requested, verify that libsvtav1 is registered.
        if codec == VideoCodec::Av1Svt {
            // SAFETY: find_encoder_by_name is always safe to call with a valid NUL-terminated
            // C string literal; the returned pointer is owned by FFmpeg and must not be freed.
            let has_svt = unsafe {
                avcodec::find_encoder_by_name(b"libsvtav1\0".as_ptr() as *const i8).is_some()
            };
            if !has_svt {
                return Err(EncodeError::EncoderUnavailable {
                    codec: "av1/svt".to_string(),
                    hint: "Requires an FFmpeg build with --enable-libsvtav1 (LGPL)".to_string(),
                });
            }
        }

        // Early check: when H265 is requested, verify that at least one HEVC encoder
        // is registered in this FFmpeg build before attempting candidate selection.
        if codec == VideoCodec::H265 {
            // SAFETY: avcodec::find_encoder is always safe to call with a valid codec ID;
            // the returned pointer is owned by FFmpeg and must not be freed.
            let has_hevc = unsafe { avcodec::find_encoder(AVCodecID_AV_CODEC_ID_HEVC).is_some() };
            if !has_hevc {
                return Err(EncodeError::EncoderUnavailable {
                    codec: "h265/hevc".to_string(),
                    hint: "Requires an FFmpeg build with HEVC encoder support \
                           (hardware: hevc_nvenc/hevc_qsv/etc.; \
                           software: --enable-libx265, GPL)"
                        .to_string(),
                });
            }
        }

        let candidates: Vec<&str> = match codec {
            VideoCodec::H264 => self.select_h264_encoder_candidates(hardware_encoder),
            VideoCodec::H265 => self.select_h265_encoder_candidates(hardware_encoder),
            VideoCodec::Vp9 => vec!["libvpx-vp9"],
            VideoCodec::Av1 => vec!["libaom-av1", "libsvtav1", "av1"],
            VideoCodec::Av1Svt => vec!["libsvtav1"],
            VideoCodec::ProRes => vec!["prores_ks", "prores"],
            VideoCodec::DnxHd => vec!["dnxhd"],
            VideoCodec::Mpeg4 => vec!["mpeg4"],
            VideoCodec::Vp8 => vec!["libvpx"],
            VideoCodec::Mpeg2 => vec!["mpeg2video"],
            VideoCodec::Mjpeg => vec!["mjpeg"],
            VideoCodec::Png => vec!["png"],
            VideoCodec::Ffv1 => vec!["ffv1"],
            _ => vec![],
        };

        // Try each candidate
        for &name in &candidates {
            unsafe {
                let c_name = CString::new(name).map_err(|_| EncodeError::Ffmpeg {
                    code: 0,
                    message: "Invalid encoder name".to_string(),
                })?;
                if avcodec::find_encoder_by_name(c_name.as_ptr()).is_some() {
                    return Ok(name.to_string());
                }
            }
        }

        Err(EncodeError::NoSuitableEncoder {
            codec: format!("{:?}", codec),
            tried: candidates.iter().map(|s| (*s).to_string()).collect(),
        })
    }

    /// Select H.264 encoder candidates with LGPL compliance.
    ///
    /// Priority order:
    /// 1. Hardware encoders (LGPL-compatible)
    /// 2. libx264 (GPL only, requires `gpl` feature)
    /// 3. VP9 fallback (LGPL-compatible)
    pub(super) fn select_h264_encoder_candidates(
        &self,
        hardware_encoder: crate::HardwareEncoder,
    ) -> Vec<&'static str> {
        let mut candidates = Vec::new();

        // Add hardware encoders based on preference
        #[cfg(feature = "hwaccel")]
        match hardware_encoder {
            crate::HardwareEncoder::Nvenc => {
                candidates.extend_from_slice(&["h264_nvenc", "h264_qsv", "h264_amf"]);
            }
            crate::HardwareEncoder::Qsv => {
                candidates.extend_from_slice(&["h264_qsv", "h264_nvenc", "h264_amf"]);
            }
            crate::HardwareEncoder::Amf => {
                candidates.extend_from_slice(&["h264_amf", "h264_nvenc", "h264_qsv"]);
            }
            crate::HardwareEncoder::VideoToolbox => {
                candidates.push("h264_videotoolbox");
            }
            crate::HardwareEncoder::Vaapi => {
                candidates.push("h264_vaapi");
            }
            crate::HardwareEncoder::Auto => {
                candidates.extend_from_slice(&[
                    "h264_nvenc",
                    "h264_qsv",
                    "h264_amf",
                    "h264_videotoolbox",
                    "h264_vaapi",
                ]);
            }
            crate::HardwareEncoder::None => {
                // Skip hardware encoders
            }
        }

        // Add GPL encoder if feature is enabled
        #[cfg(feature = "gpl")]
        {
            candidates.push("libx264");
        }

        // Add LGPL-compatible fallback (VP9)
        candidates.push("libvpx-vp9");

        candidates
    }

    /// Select H.265 encoder candidates with LGPL compliance.
    ///
    /// Priority order:
    /// 1. Hardware encoders (LGPL-compatible)
    /// 2. libx265 (GPL only, requires `gpl` feature)
    /// 3. AV1 fallback (LGPL-compatible)
    pub(super) fn select_h265_encoder_candidates(
        &self,
        hardware_encoder: crate::HardwareEncoder,
    ) -> Vec<&'static str> {
        let mut candidates = Vec::new();

        // Add hardware encoders based on preference
        #[cfg(feature = "hwaccel")]
        match hardware_encoder {
            crate::HardwareEncoder::Nvenc => {
                candidates.extend_from_slice(&["hevc_nvenc", "hevc_qsv", "hevc_amf"]);
            }
            crate::HardwareEncoder::Qsv => {
                candidates.extend_from_slice(&["hevc_qsv", "hevc_nvenc", "hevc_amf"]);
            }
            crate::HardwareEncoder::Amf => {
                candidates.extend_from_slice(&["hevc_amf", "hevc_nvenc", "hevc_qsv"]);
            }
            crate::HardwareEncoder::VideoToolbox => {
                candidates.push("hevc_videotoolbox");
            }
            crate::HardwareEncoder::Vaapi => {
                candidates.push("hevc_vaapi");
            }
            crate::HardwareEncoder::Auto => {
                candidates.extend_from_slice(&[
                    "hevc_nvenc",
                    "hevc_qsv",
                    "hevc_amf",
                    "hevc_videotoolbox",
                    "hevc_vaapi",
                ]);
            }
            crate::HardwareEncoder::None => {
                // Skip hardware encoders
            }
        }

        // Add GPL encoder if feature is enabled
        #[cfg(feature = "gpl")]
        {
            candidates.push("libx265");
        }

        // Add LGPL-compatible fallback (AV1)
        candidates.extend_from_slice(&["libaom-av1", "libsvtav1"]);

        candidates
    }
}