Support and General Use > Audio Playback, Database and Playlists
[solved] youtube aac and ffmpeg
Dr4pht:
As you can see I had to reedit my last post, because there is no problem (anymore[?]) in playing tagless mp4 files
I was about to file a bug report on this matter and created some mp4 files out of Youtube videos (no tag, tag and tag+optimize). To my surprise they all played without a problem on my Clip+. BUT I had the problem of unplayable mp4 files a few days ago and a working workaround was indeed to add some tag information.
My problem right now is that I can't remember what files/videos were causing this behavior and which Rockbox-version I was using at that time, thus I can't recreate the situation.
If the Moderators choose to erase my post(s) in order to prevent confusion, I'm OK with it.
plonk:
Just to add my experience, in case it helps:
I have a routine I wrote that downloads radio programs from the BBC iplayer, until recently I had experimented with aac/m4a, but this was brought to a head by the BBC dropping mp3 streams.
I use the following code (wrapped in a ton of lovely perl) to make the raw aac stream playable in rockbox:
ffmpeg -i file.aac -f mp4 -acodec copy -vn file.mp4
(I hate recoding because all of my linux boxes are really low power)
On my Sansa Clip+ running 3.8, some of the files I was creating wouldn't play, eventually I tracked this down to the file length. A file of 30mins long would play sometimes, 45 mins and longer never. So I rejigged the code to dump 15 minutes chunks of the program sequentially into a directory (This also speeds the download up drastically as they throttle it server side). Now they all play in rockbox perfick.
I'm assuming this is some sort of RAM limit? I can supply an hour long file if anyone wants to try it on a different player. MP4 files do seem a lot more finicky that MP3.
Now I just need to port Rockbox to ncurses, so they will play on my servers(!)
Chronon:
Long mp4/m4a files have been problematic for a while.
http://www.rockbox.org/tracker/task/8923
It looks like there has been some recent investigation on this problem.
Dr4pht:
--- Quote ---I use the following code (wrapped in a ton of lovely perl) to make the raw aac stream playable in rockbox:
ffmpeg -i file.aac -f mp4 -acodec copy -vn file.mp4
(I hate recoding because all of my linux boxes are really low power)
--- End quote ---
I want to apologize in advance if i misinterpreted your post, plonk, but I just want to point out that mp4creator in Crispin's and my code line isn't used for recoding the aac file. It simply muxes it into an appropriate container, which is a completely lossless process.
I don't know if ffmpeg is capable of producing mp4 containers with optimized layout.
Chronon:
I believe the "-acodec copy" bit should tell ffmpeg to use the same audio codec (i.e. no transcoding). No idea about the layout, though.
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