Quicktime Lion won't play MP4 files...

[Guest]

I have a large number of MP4 files encoded with Handbreak that played perfectly on all my Mac's under Snow Leopard and could be synced to my iPad.  Since upgrading to OS X Lion these files won't play in Quicktime and won't sync to my iPad.  The quicktime error message is: The document "filename.m4v" could not be opened.  A required codec isn't available. The file is being reported by finder with the following codecs: H.264, AC3, AAC, Text Can anyone help please?Thanks

[Guest]

Strange, take a look here: http://support.apple.com/kb/HT3775 Failing that you can always re-encode them with FFMPEGX (my personal favourite)

[Guest]

Thanks  - had already seen that link and unfortunately it didn't help.  So I have tracked the issue down to files that have AC3 as the first sound track as opposed to the second.  If AC3 is the first track then Lion/iTunes will not sync the file to either an iPad or an iPhone.  These did sync previosuly on Snow leopard and the iPad and iPhone played them fine and were able to select the AAC track irrespective of whether it was track 1 or track 2. So this looks like a bug in Lion/iTunes for video files with AC3 as first track not second (given that they worked perfectly previously)

[Guest]

Great! Thanks for sharing the solution/workaround. Actually this could be a major bug for a lot of people considering how big some of the libraries can be (mine included )

[Guest]

Hi Richard90, this same bug has bitten me -- movie files made by Handbrake on Lion won't play with Quicktime. They play fine with DIVX Player or VLC. Just Quicktime fails to open it. Thanks for the sleuthing that tracked it down to the sound format AC3. Two steps forward, one back.

[fadireslly]

According to Apple Support Website, QuickTime can only support MPEG-4 (.mp4, .m4v), but MP4 is a complex video container with various video and audio codecs. That's why sometimes QuickTime plays MP4 well, sometimes doesn't.

Here is a solution I just found on Macrumors forum as following:

To solve QuickTime won't play MP4 issue, a strongly recommended solution is to convert all kinds of MP4 videos and movies to QuickTime more compatible formats.

Hope it will help you more or less.