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

[Mats Peterson]

Michael Niedermayer <michael at niedermayer.cc> skrev: (11 mars 2016 15:05:49 CET)
>On Fri, Mar 11, 2016 at 02:12:56PM +0100, Mats Peterson wrote:
>> Mats Peterson <matsp888-at-yahoo.com at ffmpeg.org> skrev: (11 mars 2016
>14:06:19 CET)
>> >Mats Peterson <matsp888-at-yahoo.com at ffmpeg.org> skrev: (11 mars
>2016
>> >13:55:20 CET)
>> >>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/
>> >>_______________________________________________
>> >>ffmpeg-devel mailing list
>> >>ffmpeg-devel at ffmpeg.org
>> >>http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> >Those asv1/asv2 files play just fine with a biSize of 40, at that.
>> >
>> >Mats
>> >-- 
>> >Mats Peterson
>> >http://matsp888.no-ip.org/~mats/
>> >_______________________________________________
>> >ffmpeg-devel mailing list
>> >ffmpeg-devel at ffmpeg.org
>> >http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> 
>> Should we perhaps "tighten" the "specs" (I saw that you have written
>some documentation on asv1/asv2 in FFmpeg), and include those extra
>bytes in biSize? I suppose this is somewhat of a proprietary FFmpeg
>invention.
>
>we didnt invent ASUS video 1 and 2 nor huffyuv
>
>which codec with a non-palette global header puts 40 there ?
>
>the ms specs just says the color table & mask isnt part of biSize
>it doesnt say the global header isnt, or iam looking at the wrong text
>or location in the text/spec
>
>[...]

Again, only one I know of is HuffYUV, and the specs define a custom BITMAPINFOHEADER that includes the Huffman tables. The "global data" in ASUS is only 8 bytes. Do they regard the BITMAPINFOHEADER as being part of this global data as well? And should we? A BITMAPINFOHEADER is a BITMAPINFOHEADER is a BITMAPINFOHEADER...

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