[FFmpeg-devel] [PATCH] avformat/adxdec: demux multiple blocks at once
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Fri Sep 18 13:29:41 EEST 2020
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.
>>
>>> + 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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