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

[Mats Peterson]

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 ?
>>
>> [...]
>
> biSize should only be the size of the very BITMAPINFOHEADER, not
> including the palette or extra data. HuffYUV has its own
> BITMAPINFOHEADER, once again.
>
> Mats
>

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.

Mats