oxideav-prores

Pure-Rust Apple ProRes codec — decoder + encoder for all six ProRes video profiles (422 Proxy / LT / Standard / HQ and 4444 / 4444 XQ). 8-bit, 10-bit, and 12-bit Y'CbCr; lossless alpha plane on the 4444 / 4444 XQ profiles.

Part of the oxideav framework but usable standalone. No C libraries, no FFI wrappers, no *-sys crates.

Status

Bit-depth selection follows the stream's CodecParameters::pixel_format — RDD 36 §5 carries no per-frame bit-depth syntax element; §7.5.1 defines the conversion from reconstructed color component values to pixel samples of arbitrary bit depth b. Pass Yuv422P10Le / Yuv444P10Le to get 10-bit planar output (LE u16 pairs, valid range 0..=1023); pass Yuv422P12Le / Yuv444P12Le for 12-bit (0..=4095); pass Yuv422P / Yuv444P (or omit pixel_format) for 8-bit.

Alpha plane

The 4444 / 4444 XQ profiles support a per-pixel alpha channel coded losslessly per RDD 36 §5.3.3 + §7.1.2 (raster-scan run-length code + differential VLC, Tables 12-14). The alpha is exposed as a 4th VideoPlane on the decoded VideoFrame (after Y/Cb/Cr); the encoder accepts the same shape on input via [encoder::encode_frame_with_alpha].

The core PixelFormat enum does not yet carry Yuva422P / Yuva444P variants, so the pixel-format reporting stays as Yuv4(2|4)4P* — the caller checks frame.planes.len() == 4 to detect alpha.

The 4444 and 4444 XQ profiles share the same bitstream structure as 4444 — XQ is selected when the caller requests the highest quality tier and produces a larger packet at lower quantisation.

ffmpeg-encoded prores_ks apcn / apch (4:2:2) and ap4h (4444 + alpha) streams decode interop-clean — both progressive and interlaced (-flags +ildct -top {0,1}). Streams produced by this crate's own encoder use the spec's entropy coder for color, but the encoder emits a plain run-length alpha (alternative path permitted by §7.1.2); the coder is bit-exact with itself and decoder-compatible.

Configurable quantisation matrices (RDD 36 §5.3.4 + §6.3.7 + §7.3)

The encoder defaults to the spec's flat all-4s quantisation matrix (load_luma_qmat = load_chroma_qmat = 0, 20-byte frame header — same as prores_ks for apcn / apch when no perceptual preset is selected). Pass an [encoder::EncoderConfig] with a non-default [quant::QuantMatrices] to load custom matrices into the frame header (making the header 84 or 148 bytes per §7.3) — every RDD 36 decoder, including ffmpeg's, uses the loaded matrices for dequantisation.

A built-in perceptual preset is provided via [quant::QuantMatrices::perceptual]: JPEG K.1 / K.2 (ISO/IEC 10918-1 Annex K) normalised to a DC weight of 2 and clamped to the spec's 2..=63 weight range. At every quantization_index from 2 to 16 the perceptual matrices cut packet size by 20-25% on broadband content because the entropy coder's endOfData() semantics (RDD 36 §7.1.1) turn HF zeros into trailing zero runs that cost no bits. PSNR trades off slightly because flat is provably PSNR-optimal under uniform quantisation, but JPEG-style CSF-rolloff matrices preserve perceptual quality far better than the same byte-count flat encode.

use oxideav_prores::encoder::{make_encoder_with_config, EncoderConfig};
use oxideav_prores::quant::QuantMatrices;

let enc = make_encoder_with_config(&params, EncoderConfig::perceptual())?;
// Or: EncoderConfig::default().with_quant_matrices(QuantMatrices { luma, chroma })
# Ok::<(), Box<dyn std::error::Error>>(())

Interlaced (RDD 36 §5.1, §6.2, §7.5.3)

A frame's interlace_mode (0 = progressive, 1 = top-field-first, 2 = bottom-field-first) controls whether the encoded bitstream carries one picture or two (one per field). Source rows interleave across fields per §7.5.3: top field = source rows 0, 2, 4, …; bottom field = rows 1, 3, 5, …. The encoder splits the source into two field pictures (each at (height + 1) / 2 or height / 2 rows) and emits them in temporal order; the decoder reverses the deinterleave. Each field picture uses the interlaced block scan (§7.2 Figure 5) instead of the progressive Figure 4. See [encoder::encode_frame_interlaced].

Usage

[dependencies]
oxideav-core = "0.1"
oxideav-codec = "0.1"
oxideav-prores = "0.0"

Profile selection

The encoder picks a profile from the combination of pixel_format and bit_rate:

use oxideav_codec::CodecRegistry;
use oxideav_core::{CodecId, CodecParameters, Frame, PixelFormat};

let mut reg = CodecRegistry::new();
oxideav_prores::register(&mut reg);

let mut params = CodecParameters::video(CodecId::new("prores"));
params.width = Some(1920);
params.height = Some(1080);
params.pixel_format = Some(PixelFormat::Yuv422P);
params.bit_rate = Some(220_000_000); // -> 422 HQ

let mut enc = reg.make_encoder(&params)?;
# Ok::<(), Box<dyn std::error::Error>>(())

Codec id

• Codec: "prores"; accepted pixel formats Yuv422P, Yuv444P.
• Keyframe-only (all ProRes frames are intra).

License

MIT — see LICENSE.