Converting WMV to MP4 - audio out of sync

[wasser]

Converted a PowerPoint slide show to WMV. The WMV plays with no trouble. Audio begins at about 30 seconds as intended. I used Handbrake to convert to MP4 and now the audio starts right at the beginning. I tried adding 30 seconds of silence to the MP3 audio track, but have the same result: wmv plays fine, converted mp4 removes the silence and starts music at the beginning.

[wasser]

Playing the Mp4 with Windows Media Player eliminates the 30 second silent gap. However, when I play the same file in VLC it correctly has the 30 second gap.

[Marsia Mariner]

Try decompressing the WMA stream with Lord_Mulder's wma2wav.exe.
If the resulting .WAV file includes the 30 seconds of silence at the beginning, then you can safely convert it to MP3, or AAC, or whatever.

WMP is not a good application, don't use it.
VLC is good at playing non-compliant and broken files...
but you shoudn't be creating broken files in the first place.

[wasser]

Thanks for the reply Marsia. Extracted to wav using wma2wav.exe and the 30 second silence is there in the wav file. MP4s generated from HandBrake consistently show this oddity (WMP skips the silence/VLC plays it right).

Unfortunately I don't have control on what player will be used - the intent is to distribute this video to multiple people (about 70).

However, I found a method that results in an MP4 that plays nicely in both VLC and WMP. I converted the WMV using VLC "convert/save". WMP and VLC play the file correctly.

[Marsia Mariner]

Good to know you found an easy solution to the problem.

As for Handbrake: you really should report the problem to its developers.

(And if they say that the problem is in WMP itself, then there will be nothing we can do.)

[jagabo]

Never use WMV for an intermediate file -- that's just asking for trouble. It uses variable frame rates and that can confuse a lot of applications.