[Libav-user] Getting a Frame question

[M N]

avcodec_send_packet can produce multiple frames? Doesn't AVPacket only hold 1 frame for a video?? Only some audio codecs return multiple frames per packet.

04.09.2016, 05:14, "Charles" <linux2 at orion15.org>:
> On 09/03/2016 08:34 PM, Gonzalo Garramuño wrote:
>>  El 03/09/2016 a las 17:55, M J escribió:
>>>  Hi
>>>
>>>  while(av_read_frame(input_ctx, pkts) == 0)
>>>  {
>>>           //decoding
>>>           int ret1 = avcodec_send_packet(input_codecCtx, pkts);
>>>           int ret2 = avcodec_receive_frame(input_codecCtx, rawFrame);
>>>
>>>           //encoding
>>>           avcodec_send_frame(output_codecCtx, rawFrame);
>>>           avcodec_receive_packet(output_codecCtx, pktr);
>>>
>>>           int ret = av_interleaved_write_frame(output_ctx, pktr);
>>>  }
>>>  *************************************************
>>  Hi, MJ.
>>
>>  AFAIK, the new API does not work yet. Use the deprecated functions for the time being.
>
> It appears to work I have been decoding and encoding using the send / receive, video only.
>
> You probably need to deal with multiple conditional returns from both decode and encode.
> i.e avcodec_send_packet can produce multiple frames, you need to receive output in a loop not just the input file.
> See https://ffmpeg.org/doxygen/3.1/group__lavc__encdec.html
>
> Another possible issue may be with the setup and connecting everything.
> I had issue until the usage was correct for codecpar.
>
> Decode:
> avformat_alloc_context / avformat_open_input / avformat_find_stream_info / avcodec_find_decoder / avcodec_alloc_context3
> Then
> avcodec_parameters_to_context
> avcodec_open2
>
> Encode:
> avcodec_find_encoder / avformat_alloc_output_context2 / avcodec_alloc_context3 / avformat_new_stream / av_codec_get_tag2
> Then
> // I had to manually set the output stream codec_tag / time_base / av_stream_set_r_frame_rate
> avcodec_parameters_from_context
> avcodec_open2
>
> The parameters TO/FROM context connects most of it together.
>
> Thanks
> cco
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