[FFmpeg-devel] [PATCH 2/2] examples/decode_filter_video: Add loop for draining the filtergraph

[Tobias Rapp]

On 27/03/2024 13:06, Stefano Sabatini wrote:

> On date Wednesday 2024-03-27 11:51:31 +0100, Tobias Rapp wrote:
>> Depending on the filters used the filtergraph can produce trailing data
>> after feeding it the last input frame. Update the example to include the
>> necessary loop for draining the filtergrap.
>>
>> Signed-off-by: Tobias Rapp <t.rapp at noa-archive.com>
>> ---
>>   doc/examples/decode_filter_video.c | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>>
>> diff --git a/doc/examples/decode_filter_video.c b/doc/examples/decode_filter_video.c
>> index 454c192..a57e6df 100644
>> --- a/doc/examples/decode_filter_video.c
>> +++ b/doc/examples/decode_filter_video.c
>> @@ -276,6 +276,25 @@ int main(int argc, char **argv)
>>           }
>>           av_packet_unref(packet);
>>       }
>> +    if (ret == AVERROR_EOF) {
>> +        /* signal EOF to the filtergraph */
>> +        if (av_buffersrc_add_frame_flags(buffersrc_ctx, NULL, 0) < 0) {
>> +            av_log(NULL, AV_LOG_ERROR, "Error while closing the filtergraph\n");
>> +            goto end;
>> +        }
>> +
>> +        /* pull remaining frames from the filtergraph */
>> +        while (1) {
>> +            ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
>> +            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
>> +                break;
> how are we supposed to handle the EAGAIN case? Shouldn't this be a
> sleep and retry?

Good suggestion. I could add something like usleep(100) upon EAGAIN.

Will post an updated patch.