[FFmpeg-devel] [PATCH] webp: add support for EXIF metadata chunks

James Almer jamrial at gmail.com
Mon Jan 13 20:55:03 CET 2014


On 13/01/14 4:42 PM, James Zern wrote:
> On Mon, Jan 13, 2014 at 11:37 AM, James Almer <jamrial at gmail.com> wrote:
>> On 13/01/14 8:22 AM, Thilo Borgmann wrote:
>>> Am 13.01.14 05:37, schrieb James Almer:
>>>> [...]
>>>
>>> Nobody argued about it in mjpegdec.c and I do not know what bytestream2 does
>>> internally, but I could imagine a byte alignement could be of use here. Check
>>> with the specification, maybe it is good as it is, I'm not sure.
>>>
>>>
>>> Looks good to me otherwise - but I have no way to compile & run it right now.
>>>
>>> -Thilo
>>
>> The WebM spec doesn't mention anything beyond "Exif metadata goes inside an
>> EXIF chunk, of which there should be no more than one", and the files i
>> created with libwebp worked as it is.
> 
> The only thing worth noting is that the chunk might be padded by one
> byte to satisfy RIFF constraints regarding odd sizes.
> 

The check for padding is done for each chunk at the beginning of the while 
statement, and the code skips the entire chunk (padded or not) after the 
metadata is processed.

>> I also don't see any kind of alignment function from bytestream2 like there
>> is for getbits.
>>
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