[Ffmpeg-devel] [PATCH] correctly set profile/level for mpeg2 hd

Baptiste Coudurier baptiste.coudurier
Thu Feb 1 10:43:04 CET 2007


Baptiste Coudurier wrote:
> Michael Niedermayer wrote:
>> Hi
>>
>> On Thu, Jan 25, 2007 at 06:07:37PM +0100, Baptiste Coudurier wrote:
>>> Baptiste Coudurier wrote:
>>>> Hi
>>>>
>>>> Michael Niedermayer wrote:
>>>>>> [...]
>>>>>> Index: libavcodec/mpeg12.c
>>>>>> ===================================================================
>>>>>> --- libavcodec/mpeg12.c	(revision 7707)
>>>>>> +++ libavcodec/mpeg12.c	(working copy)
>>>>>> @@ -234,11 +234,19 @@
>>>>>>          }
>>>>>>      }
>>>>>>  
>>>>>> -    if(avctx->profile == FF_PROFILE_UNKNOWN)
>>>>>> +    if(avctx->profile == FF_PROFILE_UNKNOWN) {
>>>>>> +        if (avctx->width > 720 || avctx->height > 576)
>>>>>> +            avctx->profile = 1; /* High Profile */
>>>>>> +        else
>>>>>>          avctx->profile = s->chroma_format == CHROMA_420 ? 4 : 0;
>>>>> this is incorrect, such resolutions do not need high profile
>>>> This is correct, they do not need it, except when 422 chroma,
>>>> and we could use 422P profile when height is 608.
>>>>
>>>>>> +    }
>>>>>>  
>>>>>> -    if(avctx->level == FF_LEVEL_UNKNOWN)
>>>>>> +    if(avctx->level == FF_LEVEL_UNKNOWN) {
>>>>>> +        if (avctx->width > 720 || avctx->height > 576)
>>>>>> +            avctx->level = 4; /* High Level */
>>>>> High 1440 profile seems sufficient here
>>>>> anyway either set these values correctly or dont set them
>>>> What about 4:2:2 chroma format ? Only High profile and 4:2:2 support it
>>>> at such resolutions.
>>>> Those profile/level I set with the patch are correct,
>>>> they englobes all combinations with the smallest code.
>>>>
>>>> If you prefer, I'll use the least requiring profile for all
>>>> chroma/resolution combinations.
>>>>
>>>>> [...]
>>>>>> -                put_bits(&s->pb, 1, s->chroma_format == CHROMA_422); //escx
>>>>>> +                put_bits(&s->pb, 1, s->avctx->profile == 0); //escx 1 for 4:2:2 profile */
>>>>> my mpeg2 draft says non 0 is reserved, so this will need some
>>>>> explanations
>>>>>
>>>> Quote from ISO 13818-2 2000:
>>>> "Table 8-4 describes profiles and levels when the escape bit equals 1.
>>>> For these profiles and levels there is no implied hierarchy from the
>>>> assignment of profile_and_level_indication and profiles and levels
>>>> are not necessarily subsets of
>>>> others."
>>>>
>>>> 4:2:2 profile always use escape bit to one. Multi view profile uses it
>>>> too, but I don't know if encoder supports it.
>>>>
>>>> 10000101 4:2:2 profile @ Main level
>>>> 10000010 4:2:2 profile @ High level
>>>>
>>> Here is another patch. Is that acceptable ?
>> i guess yes, mans any comments?, my knowledge of the profile and level numbers
>> isnt that good ...
>>
> 
> Mans ?
> 

Applied.


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