Foward / Rewind performance questions

[mario595]

I have several HD 6-30 GB movies that I have muxed into an m2ts container with an h264 video stream and an AC3 audio file. I stream (not transcode) these movies to the TV via my PS3 and PC. I do a lot of rewinding during the movie play. Whether I use the RW/FF process or use the GOTO feature based on time I notice that some movies are very snappy at doing this and others take forever to position. It is not necessarily dependant on file size. My computer and disk performance is not the issue.

I don't know how the MKV files that I muxed into an m2ts were created. It seems as though there may be some kind of indexing or data in the container that affects how well these features will work. I am guessing that this data is not always present depending on how the person created the MKV files. Am I correct about this? Is there some kind of data kept in the container or the video/audio streams that affect this performance? Is there a utility that can re-build this data? In what container format?

Thanks.

[poisondeathray]

This usually depends on the keyframe interval (size between keyframes) . Longer interval = slow seeking . People use longer intervals to improve compression. Also improper vbv values (buffer) can cause this, but that usually causes stuttering, not ff/rwd issues. You cannot "fix" either without re-encoding (lose quality, takes time)

[mario595]

As a test can I take a file that does not perform well and use Ripbot to reencode and shorten this interval? What option is that? If not what software can I use to re-encode a movie to shorten the keyframe intervals on an h264 video. Is there an affect on the audio track? I have tons of disk space so size is never an issue. I shoot for the best picture quality and now I want the best FF/RW/GOTO performance as well.

[poisondeathray]

Ripbot uses 250 as the default (same as x264 default), thats usually too long for most hardware players (and probably for your streaming) . Reduce it to 24 (--keyint 24) .

Is there an affect on the audio track?

No . In fact I would copy the audio track, so you don't lose quality (incur generation loss)


Also, your compression efficiency will decrease with the shorter GOP, so I would use a much lower crf value, or higher bitrate if you don't want quality to suffer too much (not to mention that you are losing quality by re-encoding in the first place; if possible I would start from the original source - i.e. blu-ray)