On 17/05/2011 19:01, Christopher Woods (CustomMade) wrote:
I've noticed this with MP4Box as well. I think it filters
out ADTS frame headers when adding the AAC audio as a track
to the MP4 file, which would account for most of the
difference. I would guess YAMB does likewise.
It seems to be non-destructive though; when re-exporting the raw streams out
of the MP4 file the resulting filesize is identical to the original file. I
*haven't* checksummed them though (just thought about doing it) - will run
QuickSFV when I get home and report the results, I'm about to leave the
office.
Yep - I should pointed that out. The ADTS frame headers are there for
use in streaming, but when they get stripped you still have the raw AAC
audio intact inside the MP4 file - it doesn't get changed in any way, at
least not by MP4Box. When I first noticed this, I checksummed ADTS AAC
audio going in and out of MP4Box, and it's OK.
_______________________________________________
get_iplayer mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/get_iplayer
