Converting to H264 [.MP4] (mencoder) results in video playing too fast

[ChrisMtl]

Hi,

Seems like a common issue and have only found one 'supposed' solution to date, which I don't understand:

When converting an .flv file to .MP4 using H264 and mencoder, the resulting video file is a movie with the correct audio speed but with video that plays too fast. Converting this same video to .mp4 with Mpeg Streamclip has perfect results, yet I wanted to take advantage of ffmpegX's Deblock filter and it seems only ffmpegX produces this problem.

The original video's framerate is listed in Quicktime as 24.98 fps and seems to convert at 25 fps, because the resulting video starts out in sync but by the end of 93 min it was out of sync by about 4.5 seconds - almost the EXACT lag expected when the framerate is off by 0.02 seconds over a period of 92m56s. Quicktime confirms the converted video is indeed playing at 25 fps.

In ffmpegX I set the framerate to Unspecified, as there are no other options other than 23.976, 25 and 29.97.

The hint found on one forum to solve this problem was to add the switch -MC 0 to the mencoder command line. I would like to know if anyone knows of this problem and what this switch does, as I don't believe there is a way to add a manual switch to ffmpegX (but only ffmpeg)... though I'm a newbie and despite a few hours of searching, I still have no idea how to run mencoder using a command line.

Any thoughts as to if this can be solved or if whatever the -MC 0 switch does can implented using ffmpegX?

Thank you in advance.

[Case]

In ffmpegX I set the framerate to Unspecified, as there are no other options other than 23.976, 25 and 29.97.

You may enter (type in) a value of "24.98" in the framerate field. Think of the other options as common fast presets; they're not the only possible values.

[ChrisMtl]

You may enter (type in) a value of "24.98" in the framerate field. Think of the other options as common fast presets; they're not the only possible values.

Hey Case, thanks for the tip. Yes indeed you can enter a specific value, I didn't know that. There must be some bug with ffmpegX however, or maybe the H264 [.MP4] (mencoder) option doesn't accept it, because I did just that to force the framerate to 24.98 and the resulting video came out at the common 29.97 rate with once again, the audio playing perfectly.

The speeded-up video ended roughly 16 minutes short of the 92 minutes with black frames filling out the rest and the audio played fine to the end. So it seems the 24.98 framerate was not accepted and it possibly just went to a default?

[Case]

As "24.98 fps" is an unusual number for framerate, it may be that your source file has in fact variable framerate (VFR). If so, it could be a cause for sync issues. Not sure how to deal with such a beast, though.

[ChrisMtl]

I guess that's possible, it seems this is a trouble file. Thanks for all your previous help, Case.