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The docs for libav’s av_find_best_stream function (libav 11.7, Windows, i686, GPL) specify a parameter that can be used to receive a pointer to an appropriate AVCodec :

decoder_ret - if non-NULL, returns the decoder for the selected stream

There is also the avcodec_find_decoder function which can find an AVCodec given an ID.

However, the official demuxing + decoding example uses av_find_best_stream to find a stream, but chooses to use avcodec_find_decoder to find the codec in lieu of av_find_best_stream’s codec return parameter :

ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);

...

stream_index = ret;

st = fmt_ctx->streams[stream_index];

...

/* find decoder for the stream */

dec = avcodec_find_decoder(st->codecpar->codec_id);

As opposed to something like :

ret = av_find_best_stream(fmt_ctx, type, -1, -1, &dec, 0);

My question is pretty straightforward : Is there a difference between using av_find_best_stream’s return parameter vs. using avcodec_find_decoder to find the AVCodec ?

The reason I ask is because the example chose to use avcodec_find_decoder rather than the seemingly more convenient return parameter, and I can’t tell if the example did that for a specific reason or not. The documentation itself is a little spotty and disjoint, so it’s hard to tell if things like this are done for a specific important reason or not. I can’t tell if the example is implying that it "should" be done that way, or if the example author did it for some more arbitrary personal reason.