Files (.mp4) muxed by yamb do not work.

[sirdan]

Hello, i found on youtube songs that i cant find anywhere else. So i downloaded hq version (MP4) and muxed by newest beta of yamb to get rid of useless video track. But files do not play in rockbox . Copying YT's mp4 video directly to my player and files play fine (audio only of course). Is it yamb fault or rockbox? Yamb mainly is a gui for mp4box.

[yapper]

http://www.rockbox.org/twiki/bin/view/Main/PluginMpegplayer gives details of the video support in Rockbox.

[Lear]

The MP4 file is likely not optimized for streaming, which Rockbox currently needs. Selecting the option "Store file with all media data first" in YAMB should fix it (I haven't tested using it, but I get a strange message when I select the option).

[sirdan]

@Yapper
Sorry I wasnt clear. I wanted to play only remuxed audio  from youtube videoclips on rockbox.
@Lear
That error should be fixed in next release of yamb.
I used older release instead (2.0.0. and still cannot play muxed song. Keeping video track is just waste of space for me.

So... Anyone recommend nice mp4 muxer that works along with rockbox?

[Chronon]

Various tagging programs are able to move the metadata atoms to the beginning of the file.  Foobar2000 and, I believe, MP3Tag can do this.

[sirdan]

It took some time to me but i resolved my problem! And probably found bug in mp4 parser...

Firstly, for anyone interested, the best way to get rid of video track from mp4 is to use tool MP4Muxer from http://www.dvbportal.de/projects/mp4muxer/ Do it with care as this tool deletes video track from existing file.
Any optimizations by foobar or mp3tag for incompatible files (eg. created by yamb) didnt work. For them, demultiplex track to .aac and then create (multiplex) .mp4 file again. Of course by mp4muxer.

Regarding bug in RB. If i try to play incompatible mp4 file, then any mp4 will not work. Even good ones. After reset proper muxed mp4's play fine.

[Chronon]

Thanks for the info.  We have a UsefulTools page in the wiki.  If you feel this is a useful tool for this purpose you are welcome to add it. 

It sounds like you might be describing a variation of the bug described at http://www.rockbox.org/tracker/task/8664

[Lear]

Foobar2000 should do it, if you've configured it to put MP4 tags first (Advanced preferences, Tagging / MP4 / Tag location).

[sirdan]

Hmmm.. still foobar's optimizing doesnt work for me somehow.

In this case, MP4Muxer is useful indeed. I would really like to contribute rockbox. But dont know how, and anyway there are only tools for mp3. Strangely, no one thought about mp4. It would require add new entry for this format.
I think i would find time also to translate rbutility to polish, if anyone didnt start it yet. But how? (forgive me that noob question ) I suppose i should register first?

[icheyne]

That MP4Muxer tip is superb. I struggled for ages to get Ffmpeg to cleanly rip audio from youtube files but MP4Muxer does it very cleanly.