Position of mvhd chunk in m4a

[touff-ray]

Hi,

I am converting a WMA lossless file to AAC LC using the m4a Nero AAC Encoder (release 10). When using no DSP, the mvhd chunk is at the beginning of the AAC file (which is the desired output). However, when using the Id Tag Processing DSP to remove all tags, the mvhd chunk is moved to the end of the AAC file, which is a problem in my case.

Is there a way to keep the mvhd chunk at the beginning at the file when removing all tags ?

[touff-ray]

Re: Position of mvhd chunk in m4a

Forgot to add that I have this issue only with tracks longer than around 1 hour.

[Spoon]

Re: Position of mvhd chunk in m4a

The mvhd is part of the moov chunk, that has moved to the end of the file also?

[touff-ray]

Re: Position of mvhd chunk in m4a

Yes it has moved to the end of the file as well.

[Spoon]

Re: Position of mvhd chunk in m4a

What is the size of the file in question?

[touff-ray]

Re: Position of mvhd chunk in m4a

The source file is a 539MB WMA Lossless for a duration of 1 hour and 17 minutes

(and it seems like I have the same problem with the Apple Lossless codec release 14 for any duration as long as I use the DSP to remove all tags)

[Spoon]

Re: Position of mvhd chunk in m4a

Looking at the code this is to be expected, it is our ID tag writing routine which will pull the moov chunk infront of the data. If no tags are being written then the default settings from the encoder are used.

[touff-ray]

Re: Position of mvhd chunk in m4a

Then why is the moov chunk after the data when I use the ID Tag DSP, and only for very long AAC tracks ? :(

[Spoon]

Re: Position of mvhd chunk in m4a

Because our code is not being activated to move the chunk if there are no ID tags.