[FFmpeg-devel] [PATCH] avformat/adxdec: demux multiple blocks at once

[Paul B Mahol]

On Fri, Sep 18, 2020 at 12:29:41PM +0200, Andreas Rheinhardt wrote:
> Paul B Mahol:
> > On Fri, Sep 18, 2020 at 12:16:18PM +0200, Andreas Rheinhardt wrote:
> >> Paul B Mahol:
> >>> Improves decoding speed by 24x
> >>>
> >>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> >>> ---
> >>>  libavformat/adxdec.c | 23 +++++++++++++++--------
> >>>  1 file changed, 15 insertions(+), 8 deletions(-)
> >>>
> >>> diff --git a/libavformat/adxdec.c b/libavformat/adxdec.c
> >>> index ccd5049acd..0e4c251cfc 100644
> >>> --- a/libavformat/adxdec.c
> >>> +++ b/libavformat/adxdec.c
> >>> @@ -53,6 +53,9 @@ static int adx_read_packet(AVFormatContext *s, AVPacket *pkt)
> >>>      AVCodecParameters *par = s->streams[0]->codecpar;
> >>>      int ret, size;
> >>>  
> >>> +    if (avio_feof(s->pb))
> >>> +        return AVERROR_EOF;
> >>> +
> >>>      if (par->channels <= 0) {
> >>>          av_log(s, AV_LOG_ERROR, "invalid number of channels %d\n", par->channels);
> >>>          return AVERROR_INVALIDDATA;
> >>> @@ -63,16 +66,20 @@ static int adx_read_packet(AVFormatContext *s, AVPacket *pkt)
> >>>      pkt->pos = avio_tell(s->pb);
> >>>      pkt->stream_index = 0;
> >>>  
> >>> -    ret = av_get_packet(s->pb, pkt, size);
> >>> -    if (ret != size) {
> >>> -        return ret < 0 ? ret : AVERROR(EIO);
> >>> -    }
> >>> -    if (AV_RB16(pkt->data) & 0x8000) {
> >>> -        return AVERROR_EOF;
> >>> +    ret = av_get_packet(s->pb, pkt, size * 128);
> >>> +    if (ret < 0)
> >>> +        return ret;
> >>> +    if ((ret % size) && ret >= size) {
> >>
> >> So if ret < size you don't set the corrupt flag. Why?
> > 
> > Because data, that is not gonna be used at all, is discarded, instead of
> > pointlessly being passed to decoder and there errored out.
> > This happens at every single eof.
> > 
> 
> But you don't return an error if the return value is in the range
> 0..size - 1; you return the packet with the incomplete and apparently
> useless packet.

I fixed that locally too.

> 
> >>
> >>> +        size = ret - (ret % size);
> >>> +        av_shrink_packet(pkt, size);
> >>> +        pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
> >>> +    } else {
> >>> +        size = ret;
> >>>      }
> >>> +
> >>>      pkt->size     = size;
> >>
> >> This line makes no sense any more: If the first branch above is taken,
> >> av_shrink_packet() will already set the size; in the other branch,
> >> av_get_packet() already did.
> > 
> > Removed that line locally.
> > 
> >>
> >>> -    pkt->duration = 1;
> >>> -    pkt->pts      = (pkt->pos - c->header_size) / size;
> >>> +    pkt->duration = size / (BLOCK_SIZE * par->channels);
> >>> +    pkt->pts      = (pkt->pos - c->header_size) / (BLOCK_SIZE * par->channels);
> >>>  
> >>>      return 0;
> >>>  }
> >>>
> >>
> >> _______________________________________________
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> >>
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> 
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