[FFmpeg-devel] [PATCH 1/3] lavf/riffenc: Improve spec compliance

[Mats Peterson]

Michael Niedermayer <michael at niedermayer.cc> skrev: (11 mars 2016 13:49:32 CET)
>On Fri, Mar 11, 2016 at 01:28:47PM +0100, Mats Peterson wrote:
>> On 03/11/2016 01:25 PM, Mats Peterson wrote:
>> >On 03/11/2016 01:14 PM, Michael Niedermayer wrote:
>> >>On Fri, Mar 11, 2016 at 05:17:18AM +0100, Mats Peterson wrote:
>> >>>On 03/11/2016 05:10 AM, Mats Peterson wrote:
>> >>>>Forget patch 2/3 and 3/3 from the old patch set.
>> >>>>
>> >>>> From the Microsoft documentation for BITMAPINFOHEADER at
>>
>>>>>https://msdn.microsoft.com/en-us/library/windows/desktop/dd318229%28v=vs.85%29.aspx:
>> >>>>
>> >>>>
>> >>>>
>> >>>>"biSize: Specifies the number of bytes required by the structure.
>This
>> >>>>value does not include the size of the color table or the size of
>the
>> >>>>color masks, if they are appended to the end of structure."
>> >>>>
>> >>>>So, biSize is always 40. Also, Windows Media Player won't detect
>video
>> >>>>encoded with Microsoft Video 1 in 8 bpp mode if this value is
>anything
>> >>>>else than 40. I don't know about other codecs, they probably
>work.
>> >>>>Anyway, we should stick with the specs, and not include the
>palette
>> >>>>size
>> >>>>in that field.
>> >>>>
>> >>>>Regarding the biClrUsed field, I'm setting it to 1 <<
>> >>>>bits_per_coded_sample if palettized video, since setting it to 0
>is
>> >>>>another case where it won't work with Windows Media Player and
>> >>>>Microsoft
>> >>>>Video 1 in 8 bpp mode.
>> >>>>
>> >>>>Mats
>> >>>>
>> >>>>
>> >>>>
>> >>>
>> >>>Once, again, HuffYUV has its own variant of BITMAPINFOHEADER that
>> >>>*does* include the size of the Huffman tables in biSize. That's
>the
>> >>>only exception as far as I know.
>> >>
>> >>is huffyuv really the exception ? and not raw rgb or palettes ?
>> >>
>> >>asv1 and asv2 do not have 40 there
>
>> >>which codec with a non-palette global header puts 40 there ?
>
>[...]
>
>> As I said before, Microsoft Video 1 in 8-bit mode and RLE4/RLE8
>> won't even display in Windows Media Player if this value is anything
>> else than 40.
>
>msv1 / RLE4/8 doesnt have a "Non palette global header"
>
>
>[...]

That's correct. Sorry. Anyway, the only case I know of is HuffYUV with its special variant of BITMAPINFOHEADER that includes the Huffman tables. Is there stated anywhere in the ASUS specs that the size of the extra data following the BITMAPINFOHEADER should be included in biSize? If not, it should be 40.

Mats
-- 
Mats Peterson
http://matsp888.no-ip.org/~mats/