[Libav-user] Getting a Frame question

[Charles]

On 09/04/2016 10:52 AM, M N wrote:
> Gonzalo then how should I continue to read packets from input format context and write them to output format context?
>
> 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

MJ,
I probably wasn't clear, each call is dependent on the return value of the previous call.
i.e. if you did not get return 0 or EAGIN from send_packet you should probably not call receive_frame

>>>>
>>>>  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);

Why don't you just print the return values. SEE av_strerror
https://ffmpeg.org/doxygen/3.1/group__lavu__error.html#ga5792b4a2d18d7d9cb0efbcfc335dce24

>>>>
>>>>           //encoding
>>>>           avcodec_send_frame(output_codecCtx, rawFrame);
>>>>           avcodec_receive_packet(output_codecCtx, pktr);

These have return values also.

>>>>
>>>>           int ret = av_interleaved_write_frame(output_ctx, pktr);
>>>>  }
>>>>  *************************************************
>>>  Hi, MJ.

Assuming everything is setup correctly, and 1 frame -> 1 packet && 1 packet -> 1 frame

while ( av_read_frame == 0 )
    if avcodec_send_packet == 0
       if avcodec_receive_frame == 0
          if avcodec_send_frame == 0
             if avcodec_receive_packet == 0
                av_interleaved_write_frame

But, each of those IF's have multiple return values
What are you going to do if the return is AVERROR(EAGAIN) or AVERROR_EOF
What about the frame delay on the encoder?

Thanks
cco