[Mp4-tech] Encrypting AVC encoded elementary streams with ISMACryp

[Dave Singer]

At 15:43  +0100 1/12/05, Cengiz Tas wrote:
>Hi all,
>
>I have integrated AVC/H.264 ISMACryp support within the mpeg4ip project and
>encountered the following problem:
>
>According to the ISMACryp spec the mp4v box of an encrypted MPEG-4 Video
>(simple) has to be substituted with the encv box with the esds box as child,
>etc. When creating AVC-Content I have an avc1 box with avcC as child and no
>esds box anymore. How does the box structure for an ISMA encrypted AVC file
>looks like? I have an idea but couldn´t find any information in the specs.
>Is it sufficient to create the encv box with the avc1/avcC boxes as
>children? Or do I have to add the esds box, too ?

The sample entry transformation for any ISMACryp 
content is quite simple.  In general (off the top 
of my head):
a) replace the sample entry name with encX where X is a, v etc.
b) add an original format atom to the entry with the original 4CC in it
c) add the sinf atom to the entry with the protection information in it
d) leave all other atoms alone, unencrypted, still in the sample entry.
Does that help?
By the way, ISMA is currently doing 
exchange-testing of ISMACryp files, including 
encrypted AVC;  you might like to take part.  See 
www.isma.tv.
-- 
David Singer
Apple Computer/QuickTime