oxideav-h261

Pure-Rust ITU-T H.261 video decoder — the original 1990/1993 videoconferencing codec. Decodes both I-pictures (INTRA macroblocks) and P-pictures (INTER with integer-pel motion compensation + optional loop filter). QCIF (176×144) and CIF (352×288) source formats. Output is YUV 4:2:0. Zero C dependencies.

Part of the oxideav framework but usable standalone.

Installation

[dependencies]
oxideav-core = "0.1"
oxideav-codec = "0.1"
oxideav-h261 = "0.0"

Feature matrix

Feature	Decode
Picture header (PSC / TR / PTYPE / PEI / PSPARE)	yes
GOB layer (GBSC / GN / GQUANT / GEI / GSPARE)	yes
Source formats QCIF (176×144), CIF (352×288)	yes
Macroblock layer (MBA / MTYPE / CBP / MVD)	yes
TCOEFF VLC + escape	yes
8×8 IDCT, dequantisation (Table 5/H.261)	yes
INTRA and INTER prediction	yes
Integer-pel motion compensation (MC)	yes
Loop filter (FIL, §3.2.3)	yes
BCH forward error correction (§5.4)	no

H.261 only permits integer-pel motion vectors (range ±15); there are no half-pel refinements, no B-pictures, and no start-code emulation prevention. The spec tables (MBA / MTYPE / MVD / CBP / TCOEFF) are all implemented directly from the PDF.

Quick use

use oxideav_codec::Decoder;
use oxideav_core::{CodecId, Packet, TimeBase};
use oxideav_h261::decoder::H261Decoder;

let mut dec = H261Decoder::new(CodecId::new(oxideav_h261::CODEC_ID_STR));
let pkt = Packet::new(0, TimeBase::new(1, 30), bitstream_bytes);
dec.send_packet(&pkt)?;
match dec.receive_frame() {
    Ok(oxideav_core::Frame::Video(vf)) => {
        // vf.format == PixelFormat::Yuv420P
    }
    Err(oxideav_core::Error::NeedMore) => { /* feed more packets */ }
    Err(e) => return Err(e.into()),
    _ => {}
}
# Ok::<(), oxideav_core::Error>(())

Codec ID

Codec: "h261"; accepted pixel format Yuv420P; dimensions QCIF or CIF.
AVI FourCC H261 maps to this id.

License