[Bug]: ffmpeg decoder not parsing and decoding all audio samples

[pfeatherstone]

What Operating System(s) are you seeing this problem on?

Linux (x86-64)

dlib version

master

Python version

No response

Compiler

gcc 12.3

Expected Behavior

I am comparing how many audio samples are decoded on a particular audio file with a particular codec, i.e. dlib/test/ffmpeg_data/116-288045-0000.flac using both the decoder object and the demuxer object. I can use the decoder in this instance since FLAC is a codec without a container.
I expect both to decode the same number of audio samples. They don't.

Current Behavior

They don't decode the same number of audio samples.

Steps to Reproduce

./buildExamples/Debug/ffmpeg_video_demuxing2_ex -i dlib/test/ffmpeg_data/116-288045-0000.flac
./buildExamples/Debug/ffmpeg_video_decoding2_ex -i dlib/test/ffmpeg_data/116-288045-0000.flac --codec flac

You get the following output:

Read 170400 audio samples

and

Read 139264 audio samples

Anything else?

I get this with FFmpeg version 6.1.1 and 4.4.2. So I imagine the bug is in the ffmpeg wrappers in dlib.

[pfeatherstone]

I've tried the decode_audio.c example in the FFmpeg repository and I get a similar result. Maybe there is something funny with the AVCodecParserContext object and/or FLAC. Will investigate.

[pfeatherstone]

Think i found the error. The example code in decode_audio.c in the FFmpeg repository is incorrect. They really need to update their own examples and check them. They get lazy with their own API... I'll submit a PR.