[FFmpeg-devel] [PATCH v9] lavc/rawdec: Remove monowhite switching code for 1 bpp AVI without a palette

Mats Peterson matsp888 at yahoo.com
Sat Feb 13 13:03:26 CET 2016


On 02/13/2016 01:00 PM, Mats Peterson wrote:
> On 02/13/2016 12:58 PM, Mats Peterson wrote:
>> On 02/13/2016 12:57 PM, Mats Peterson wrote:
>>> On 02/13/2016 12:54 PM, Mats Peterson wrote:
>>>> On 02/13/2016 12:52 PM, Mats Peterson wrote:
>>>>>>> just double checked, this is not the case in written pal8 nut files
>>>>>>> nor does the nut spec say anything about that.
>>>>>>>
>>>>>>
>>>>>> Then check an odd-width nut file like the one below. And FFmpeg
>>>>>> doesn't
>>>>>> care about specs when using "-vcodec copy". The stride will be the
>>>>>> one
>>>>>> of the original data, whether it's 2, 4 or some other amount of
>>>>>> bytes.
>>>>>>
>>>>
>>>> The stride will be *aligned* to 2, 4 or some other amount of bytes.
>>>>
>>>> Mats
>>>>
>>>
>>> Try "ffmpeg -i 8bpp_129.avi -vcodec rawvideo 8bpp_129.nut" with the file
>>> below. It will have a stride aligned to 4 bytes like the original AVI
>>> file, and per the Microsoft specification, since it doesn't "-vcodec
>>> copy" won't touch the video data.
>>>
>>> https://drive.google.com/open?id=0B3_pEBoLs0faekxWUTdkVGNTTlk
>>> _______________________________________________
>>
>> I mean "ffmpeg -i 8bpp_129.avi -vcodec copy 8bpp_129.nut" of course.
>>
>> Mats
>>
>
> The stride will be 132 bytes, divisible by 4, rather than 129 bytes.
>
> Mats
>

Now the problem is that it won't show any video, since the incorrect 
codec tag RGB[15] will be written to the nut file, and it's not possible 
to use "-vtag" to set tha PAL[8] codec tag, but if you use "-v debug" 
you will see that the stride is 132 bytes.

Mats



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