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

[Paul B Mahol]

On Thu, Aug 24, 2023 at 9:54 PM James Almer <jamrial at gmail.com> wrote:

> 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.
>

Will use ELEMS_ARRAY macro.


> > +        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).
>

Fixed.


>
> > +    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.
>

version is passed via extradata, its more cleaner approach.


>
> > +
> > +    s->bitstream = av_calloc(s->max_framesize +
> AV_INPUT_BUFFER_PADDING_SIZE, sizeof(*s->bitstream));
>
> av_mallocz(). sizeof(*s->bitstream) is 1.
>

nit, i think it changes effectively nothing.


> > +    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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