On Sat, 21 Jan 2017 10:27:30 -0700 pkoshe...@gmail.com wrote: > From: Pavel Koshevoy <pkoshe...@gmail.com> > > Evidently CUVID doesn't support decoding 422 or 444 chroma formats, > and only a limited set of resolutions per codec are supported. > > Unfortunately CUVID silently drops packets for video of unsupported > resolution. However, it will error-out at cuvidCreateDecoder call > if the indicated video resolution is not supported. > > Given that stream resolution and pixel format are typically known as > a result of probing it is better to use this information during > avcodec_open2 call to fail immediately, rather than proceeding to > decode and never receiving any frames from the decoder nor receiving > any indication of decode failure.
So I'm confused. I agree that these errors do not emerge early enough to induce failure at decoder init time, but they should all trigger errors at first-frame decode time. That's certainly true for the chroma format error, because I added that logic. Assuming that is true, you should just be dealing with first-frame failure and then falling back to SW decoding, or whatever policy you want in your app (I assume 8K SW decoding won't go well...). Sure, it's not great that you can't get failures at init time, but you have to be prepared to encounter fatal errors on frame decode with dealing with hardware decoders. Most, if not all, have failure cases that only emerge when decoding a real frame. There's a useful discussion to have about clearly indicating how fatal an error is from that frame decode failure (so we know that it's due to unsupported characteristics rather than a single bad frame), but this change won't help us get there. And I'll repeat wm4's warning that these tests depend on the presence of probed data that cannot be assumed in the general case; it may work for your app, but other applications may not fill in those fields, so it cannot be considered reliable functionality. Thanks, --phil _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
