[FFmpeg-devel] [PATCH v2] avfilter: take_samples: do not directly return frame when samples are skipped

[Muhammad Faiz]

On Sat, May 20, 2017 at 7:33 PM, Muhammad Faiz <mfcc64 at gmail.com> wrote:
> On Sat, May 20, 2017 at 5:44 PM, Muhammad Faiz <mfcc64 at gmail.com> wrote:
>> Modifying data pointer when skipping samples may make it unaligned.
>> Workaround for Ticket6349.
>>
>> This should fix the crash of ticket's testcase and a crash/regression
>> with avxsynth (reported by Michael Niedermayer).
>>
>> Also change frame->nb_samples < max to frame->nb_samples <= max.
>> This improves performance. Benchmark:
>> ./ffmpeg -filter_complex "aevalsrc=0:n=1166,firequalizer=fixed=on" -f null null
>> old:
>>   25767 decicycles in take_samples,    1023 runs,      1 skips
>>   25422 decicycles in take_samples,    2047 runs,      1 skips
>>   25181 decicycles in take_samples,    4095 runs,      1 skips
>>   24904 decicycles in take_samples,    8191 runs,      1 skips
>>
>> new:
>>     550 decicycles in take_samples,    1024 runs,      0 skips
>>     548 decicycles in take_samples,    2048 runs,      0 skips
>>     545 decicycles in take_samples,    4096 runs,      0 skips
>>     544 decicycles in take_samples,    8192 runs,      0 skips
>>
>> Signed-off-by: Muhammad Faiz <mfcc64 at gmail.com>
>> ---
>>  libavfilter/avfilter.c   | 8 +++++++-
>>  libavfilter/framequeue.c | 2 ++
>>  libavfilter/framequeue.h | 5 +++++
>>  3 files changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
>> index 08b86b0..e60b024 100644
>> --- a/libavfilter/avfilter.c
>> +++ b/libavfilter/avfilter.c
>> @@ -1191,7 +1191,7 @@ static int take_samples(AVFilterLink *link, unsigned min, unsigned max,
>>         called with enough samples. */
>>      av_assert1(samples_ready(link, link->min_samples));
>>      frame0 = frame = ff_framequeue_peek(&link->fifo, 0);
>> -    if (frame->nb_samples >= min && frame->nb_samples < max) {
>> +    if (!link->fifo.samples_skipped && frame->nb_samples >= min && frame->nb_samples <= max) {
>>          *rframe = ff_framequeue_take(&link->fifo);
>>          return 0;
>>      }
>> @@ -1522,6 +1522,12 @@ int ff_inlink_consume_frame(AVFilterLink *link, AVFrame **rframe)
>>      *rframe = NULL;
>>      if (!ff_inlink_check_available_frame(link))
>>          return 0;
>> +
>> +    if (link->fifo.samples_skipped) {
>> +        frame = ff_framequeue_peek(&link->fifo, 0);
>> +        return ff_inlink_consume_samples(link, frame->nb_samples, frame->nb_samples, rframe);
>> +    }
>> +
>>      frame = ff_framequeue_take(&link->fifo);
>>      consume_update(link, frame);
>>      *rframe = frame;
>> diff --git a/libavfilter/framequeue.c b/libavfilter/framequeue.c
>> index 26bfa49..fed1118 100644
>> --- a/libavfilter/framequeue.c
>> +++ b/libavfilter/framequeue.c
>> @@ -107,6 +107,7 @@ AVFrame *ff_framequeue_take(FFFrameQueue *fq)
>>      fq->tail &= fq->allocated - 1;
>>      fq->total_frames_tail++;
>>      fq->total_samples_tail += b->frame->nb_samples;
>> +    fq->samples_skipped = 0;
>>      check_consistency(fq);
>>      return b->frame;
>>  }
>> @@ -146,5 +147,6 @@ void ff_framequeue_skip_samples(FFFrameQueue *fq, size_t samples, AVRational tim
>>      for (i = 0; i < planes && i < AV_NUM_DATA_POINTERS; i++)
>>          b->frame->data[i] = b->frame->extended_data[i];
>>      fq->total_samples_tail += samples;
>> +    fq->samples_skipped = 1;
>>      ff_framequeue_update_peeked(fq, 0);
>>  }
>> diff --git a/libavfilter/framequeue.h b/libavfilter/framequeue.h
>> index 5aa2c72..c49d872 100644
>> --- a/libavfilter/framequeue.h
>> +++ b/libavfilter/framequeue.h
>> @@ -100,6 +100,11 @@ typedef struct FFFrameQueue {
>>       */
>>      uint64_t total_samples_tail;
>>
>> +    /**
>> +     * Indicate that samples are skipped
>> +     */
>> +    int samples_skipped;
>> +
>>  } FFFrameQueue;
>>
>>  /**
>> --
>> 2.9.3
>>
>
> I will push this soon.
>
> Thank's.

Pushed and backported to 3.3 branch.

Thank's.