Very Choppy Preview of H.264

[jv13613]

When previewing AVCHD (AVCHD is encoded in H.264) the video is extremely choppy, as well as the audio. Even playback of the media files in VLC Player is choppy. Doing a quick google search I found this. http://www.blog.arun-prabha.com/2010/03/02/how-to-play-m2ts-files-smoothly-using-vlc/ If "Skip the loop filter for H.264 decoding" is changed in VLC Player to BiDir it can play back smoothly. It decreases the video quality a little bit but plays smoothly. (And since this would be used for the preview, quality does not matter as much.) I think something like this might be available in OpenShot. (Does Openshot use the same H.264 libraries as VLC Player?) Anyway the preview is so choppy it is not is suitable for editing. The ACVHD clips were recoded at 17mbps. There are no effects or transitions on the clips.

Ubuntu 10.04
Software Center
1.1.3

[Andy Finch (fincha)]

Please follow this FAQ:

https://answers.launchpad.net/openshot/+faq/983

Any "Skip the loop filter for H.264 decoding" type setting will be a configuration/compilation flag at the MLT/FFMpeg level, but I don't know if such an option even exists in either of those libraries.

[jv13613 (jv13613)]

My video plays back fine, just slow because of the maxed out CPU.

In VLC, if you switch to advanced view of settings, you can that the option is under the ffmpeg decoding section. After some googling, I have narrowed it down to libavcodec. http://sites.google.com/site/linuxencoding/x264-ffmpeg-mapping look at the -flags +loop part. I am assuming that Openshot or MLT uses ffmpeg to play the preview of the project.

[jv13613 (jv13613)]

And I agree with you, I don't know how to do this not from the commanline. (that previous link shows command line parameters.) I wonder how one could access this feature from a library.

[Laurent Dinclaux (dreadlox)]

Same issue here. I have moved some recorded TS files from my media box and converted them to m4v using handbrake default hight profile. Openshot can't preview those files whereas pitivi can. The TS files as it (h264+aac) are previewable but very choppy

[123vier (flowrist)]

Same here, although any other player or video editor I've used plays it just fine.
My system should have no problem (AMD 3.6 Ghz Quad, 8GB Ram) handling the preview.

[Andy Finch (fincha)]

Try changing to 'sdl_preview' output mode in the Preferences.

[Andy Finch (fincha)]

There has been a recent change in the MLT library which makes AVCHD files a lot more usable - you need to have > v0.9.1 of the ffmpeg libraries (not libav) and v0.7.9 of MLT.