Decode

The mirror of encode: VideoDecoder’s push_packet / poll_frame / flush shape, dispatched cross-platform through platform::AutoDecoder.

Push / poll

let config = VideoDecoderConfig {
    extra_data,
    output: VideoOutputPreference::CpuFramesOk,
    ..VideoDecoderConfig::h264(320, 240, Rational::new(1, 30))
};
let mut decoder = platform::AutoDecoder::open(&config)?;

decoder.push_packet(&packet)?;
while let Some(frame) = decoder.poll_frame()? {
    // decoded pixel data
}

Same reasoning as encode: a decoder may hold packets internally waiting for a full frame’s worth of data (B-frame reordering again), so a packet going in doesn’t promise a frame coming out on that same call.

extra_data matters

extra_data carries the codec’s out-of-band configuration — SPS/PPS for H.264, wrapped as avcC. Get this from wherever the bitstream came from (a demuxed StreamInfo::Video::extra_data, or an encoder’s own stream_info() if you’re decoding what you just encoded, as the example below does).

Zero-Copy output

Like encode, VideoDecoderConfig::output controls the cost ladder: ZeroCopyGpu keeps decoded frames GPU-resident (paired with a gpu_device); CpuFramesOk accepts a CPU readback when there’s no GPU path, or none is needed.

Try it

cargo run --example decode_h264

examples/decode/decode_h264.rs is the complete, compiling version. It encodes a few frames first purely to have real H.264 bytes to feed the decoder — that setup step isn’t the point of the example, decode is.

For a full edit built from decode + encode together, see Pipelines.