14b4 - when is h264 decoding offloaded?

Are there only specific cases where h264 decoding is offloaded?

I have an AVCHD MTS file from a Sony camera, and Resolve is offloading its playback. However, when I transcode that same file to a MOV container, leaving video untouched but transcoding audio to PCM, Resolve is decoding it in software.

(I know it's decoding in software in the latter case because there are 4 active threads in msmpeg2vdec.dll, as it was with b3, but these threads aren't busy when playing back the original MTS file. Same video stream in either case however.)

Thanks,
Jason.

Maybe it's playback versus export case.

What gpu are you using, and what type of footage is it?

https://developer.nvidia.com/nvidia-vid ... ECFeatures

I don't think so, since both observations I mentioned in my OP were about playback. One played back offloaded, the other didn't. Same video stream, just different container and audio codec.

What gpu are you using, and what type of footage is it?

NVIDIA 1080 Ti. It's a 60p h264 AVCHD file from a Sony DSC-HX9V camera in the first case (which was offloaded), and the second case was transcoded to a MOV file using Convert 4, while preserving the video stream and converting the AC3 audio stream to PCM (which was not offloaded).

I need to stress here that in the two cases I mentioned, it's the same video stream. It didn't touch the video. Just transcoded audio and muxed to a different container (MOV vs MTS).

Container maybe the reason also. It's fairly common that decoding goes through different route depending on the container.

Container maybe the reason also. It's fairly common that decoding goes through different route depending not the container.

You're probably right. I've worked on video software with a much saner design (independent demuxing, decoding, and rendering layers) but only BMD can say what Resolve is doing here.

Maybe/hopefully it's just a matter of a small tweak to send h264 within MOV files to the accelerated path. Not sure if this is relevant, but I don't have QuickTime installed (since Apple has long discontinued it on Windows).

Maybe/hopefully it's just a matter of a small tweak to send h264 within MOV files to the accelerated path. Not sure if this is relevant, but I don't have QuickTime installed (since Apple has long discontinued it on Windows).

This is possible, but quite often shortcuts are done to simplify things. For example Edius use to do the same- h264 in MOV was decoded by poor QT engine on PC, even if Edius had very powerful own AVC decoder. Later they changed it and it was like day and night It maybe exactly the same case for Resolve.

change the extension from mov to mp4 and see if that makes a difference. I've used this "hack" over the years on several editors.

change the extension from mov to mp4 and see if that makes a difference. I've used this "hack" over the years on several editors.

That was just clever enough to work. Unfortunately it didn't.

One other significant detail: although the video streams are the same, the fourcc reported in the MOV file is 'avc1', while in the original MTS it's 'HDPR'. In the former case (where offload is not occurring) Resolve's metadata panel reports it as h.264, and in the latter case (where offload is occurring) it reports it as AVCHD.

To be honest I might have expected the opposite behavior.