Re: [FFmpeg-devel] [PATCH] OSQ lossless audio format support

[James Almer <jamrial@gmail.com>]

On 8/24/2023 6:52 AM, Paul B Mahol wrote:
> Patches attached.
> 
> Stereo decoding have some issues with some predictors so not yet bitexact.
> 
> Please comment.

> +static av_cold int osq_close(AVCodecContext *avctx)
> +{
> +    OSQContext *s = avctx->priv_data;
> +
> +    av_freep(&s->bitstream);
> +    s->bitstream_size = 0;
> +
> +    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++)

FFMIN(avctx->ch_layout.nb_channels, 2);

This being a FF_CODEC_CAP_INIT_CLEANUP decoder, osq_close() could be 
called before osq_init() has a chance to validate nb_channels.

> +        av_freep(&s->decode_buffer[ch]);
> +
> +    return 0;
> +}
> +
> static av_cold int osq_init(AVCodecContext *avctx)
> +{
> +    OSQContext *s = avctx->priv_data;
> +
> +    if (avctx->extradata_size < 48)
> +        return AVERROR(EINVAL);
> +
> +    if (avctx->extradata[0] != 1) {
> +        av_log(avctx, AV_LOG_ERROR, "Unsupported version.\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    avctx->sample_rate = AV_RL32(avctx->extradata + 4);
> +    if (avctx->sample_rate < 1)
> +        return AVERROR_INVALIDDATA;
> +
> +    avctx->ch_layout.nb_channels = avctx->extradata[3];

You'd need to uninit ch_layout first, as the user may have filled it 
with something (as is the case with the lavf demuxer).

> +    if (avctx->ch_layout.nb_channels < 1)
> +        return AVERROR_INVALIDDATA;
> +
> +    switch (avctx->extradata[2]) {
> +    case  8: avctx->sample_fmt = AV_SAMPLE_FMT_U8P; break;
> +    case 16: avctx->sample_fmt = AV_SAMPLE_FMT_S16P; break;
> +    case 20:
> +    case 24:
> +    case 28:
> +    case 32: avctx->sample_fmt = AV_SAMPLE_FMT_S32P; break;
> +    default: return AVERROR_INVALIDDATA;
> +    }
> +
> +    s->nb_samples = AV_RL64(avctx->extradata + 16);
> +    s->frame_samples = AV_RL16(avctx->extradata + 8);
> +    s->max_framesize = (s->frame_samples * 16 + 1024) * avctx->ch_layout.nb_channels;

Do you even need to propagate this header using extradata? You can set 
codecpar's sample_fmt and frame_size in the demuxer, much like you're 
doing for sample_rate and ch_layout.
There doesn't seem to be a value that can't be propagated using the 
proper existing fields here.

> +
> +    s->bitstream = av_calloc(s->max_framesize + AV_INPUT_BUFFER_PADDING_SIZE, sizeof(*s->bitstream));

av_mallocz(). sizeof(*s->bitstream) is 1.

> +    if (!s->bitstream)
> +        return AVERROR(ENOMEM);
> +
> +    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
> +        s->decode_buffer[ch] = av_calloc(s->frame_samples + 4,
> +                                         sizeof(*s->decode_buffer[ch]));
> +        if (!s->decode_buffer[ch])
> +            return AVERROR(ENOMEM);
> +    }
> +
> +    s->pkt = avctx->internal->in_pkt;
> +
> +    return 0;
> +}
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