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

[Andreas Rheinhardt]

James Almer:
> 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);
> 

Easier to just use FF_ARRAY_ELEMS(s->decoder_buffer). No harm in freeing
a NULL.

> 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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