[FFmpeg-devel] [PATCH 1/2] MxPEG decoder

[Anatoly Nenashev]

On 01.11.2010 15:08, Michael Niedermayer wrote:
> On Mon, Nov 01, 2010 at 02:55:26PM +0300, Anatoly Nenashev wrote:
>    
>> On 01.11.2010 14:35, Michael Niedermayer wrote:
>>      
>>> On Mon, Nov 01, 2010 at 02:06:25AM +0300, Anatoly Nenashev wrote:
>>>
>>>        
>>>> On 01.11.2010 00:44, Michael Niedermayer wrote:
>>>>
>>>>          
>>>>> On Sun, Oct 31, 2010 at 09:20:34PM +0300, Anatoly Nenashev wrote:
>>>>> [...]
>>>>>
>>>>>
>>>>>            
>>>>>> @@ -195,6 +198,37 @@ int ff_mjpeg_decode_dht(MJpegDecodeContext *s)
>>>>>>         return 0;
>>>>>>     }
>>>>>>
>>>>>> +static int mjpeg_allocate_picture(MJpegDecodeContext *s)
>>>>>> +{
>>>>>> +    if(s->picture.data[0])
>>>>>> +        s->avctx->release_buffer(s->avctx,&s->picture);
>>>>>> +
>>>>>> +    s->picture.reference= 0;
>>>>>> +    if(s->avctx->get_buffer(s->avctx,&s->picture)<    0){
>>>>>> +        av_log(s->avctx, AV_LOG_ERROR, "mjpeg get_buffer() failed\n");
>>>>>> +        return -1;
>>>>>> +    }
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int mxpeg_allocate_picture(MJpegDecodeContext *s)
>>>>>> +{
>>>>>> +    if (s->mxctx.reference_picture.data[0])
>>>>>> +        s->avctx->release_buffer(s->avctx,&s->mxctx.reference_picture);
>>>>>> +    s->mxctx.reference_picture = s->picture;
>>>>>>
>>>>>>
>>>>>>              
>>>>>
>>>>>            
>>>>>> +    s->picture.data[0] = s->picture.data[1] =
>>>>>> +        s->picture.data[2] = s->picture.data[3] = 0;
>>>>>>
>>>>>>
>>>>>>              
>>>>> the indention is odd
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> Just a feature of Emacs. Indention removed.
>>>>
>>>>
>>>>          
>>>>>
>>>>>            
>>>>>> +
>>>>>> +    s->picture.reference= 1;
>>>>>>
>>>>>>
>>>>>>              
>>>>>
>>>>>            
>>>>>> +    if(s->avctx->get_buffer(s->avctx,&s->picture)<    0){
>>>>>> +        av_log(s->avctx, AV_LOG_ERROR, "mxpeg get_buffer() failed\n");
>>>>>> +        return -1;
>>>>>> +    }
>>>>>>
>>>>>>
>>>>>>              
>>>>> duplicate code
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> May be not because "mxpeg_allocate_picture" used in two places:
>>>> ff_mjpeg_decode_sof and mxpeg_decode_mxm.
>>>>
>>>>
>>>>          
>>>>> [...]
>>>>>
>>>>>
>>>>>            
>>>>>> @@ -788,14 +823,29 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, i
>>>>>>             }
>>>>>>         }
>>>>>>
>>>>>> +    if (use_mxm_bitmask) {
>>>>>> +        if (s->mb_width*s->mb_height>    (s->mxctx.mxm_bitmask_size<<    3)) {
>>>>>> +            av_log(s->avctx, AV_LOG_ERROR, "MXM bitmask is not complete\n");
>>>>>> +            return -1;
>>>>>> +        }
>>>>>> +
>>>>>> +        init_get_bits(&mxm_bitmask_gb, s->mxctx.mxm_bitmask,
>>>>>> +                      s->mxctx.mxm_bitmask_size<<    3);
>>>>>> +
>>>>>> +        s->picture.pict_type= FF_P_TYPE;
>>>>>> +        s->picture.key_frame= 0;
>>>>>> +    }
>>>>>>         for(mb_y = 0; mb_y<    s->mb_height; mb_y++) {
>>>>>>             for(mb_x = 0; mb_x<    s->mb_width; mb_x++) {
>>>>>> +            const int copy_mb = use_mxm_bitmask&&    !get_bits1(&mxm_bitmask_gb);
>>>>>> +            if (!reference_picture_avail&&    copy_mb) continue;
>>>>>>
>>>>>>
>>>>>>              
>>>>> cant use_mxm_bitmask be 0 when !reference_picture_avail
>>>>> (would avoid 1 check per mb)
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> Fixed. Conditions are switched in "if()".
>>>>
>>>>
>>>>          
>>>>> [...]
>>>>>
>>>>>
>>>>>            
>>>>>> @@ -1505,6 +1631,15 @@ not_the_end:
>>>>>>     the_end:
>>>>>>         av_log(avctx, AV_LOG_DEBUG, "mjpeg decode frame unused %td bytes\n", buf_end - buf_ptr);
>>>>>>     //    return buf_end - buf_ptr;
>>>>>> +
>>>>>> +    if (s->avctx->codec_id == CODEC_ID_MXPEG&&
>>>>>> +        !s->mxctx.has_complete_frame) {
>>>>>> +        if (s->picture.key_frame)
>>>>>> +            s->mxctx.has_complete_frame = 1;
>>>>>>
>>>>>>
>>>>>>              
>>>>>
>>>>>            
>>>>>> +        else if (!(s->avctx->flags&    CODEC_FLAG_LOW_DELAY))
>>>>>> +            *data_size = 0;
>>>>>>
>>>>>>
>>>>>>              
>>>>> mxpeg is always low delay, unless i misunderstand something
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> Not absolutely so. Generally there's no I-Frame concept for MxPEG known
>>>> from other codecs. Every encoded frame contains some parts of all image.
>>>> All that we know is after fixed time delay we can collect a full puzzle.
>>>> Actually some cameras send full JPEG  frame in connection and this
>>>> feature is supported in attached patch but this is not that case on
>>>> which it is necessary to rely. That's why if CODEC_FLAG_LOW_DELAY is
>>>> disabled the decoder must collect a full image before return a first
>>>> decoded frame. Otherwise, if CODEC_FLAG_LOW_DELAY is enabled we may see
>>>> a frame full of holes at the start of played video.
>>>>
>>>>          
>>> i see what you are trying to do but thats misusing that flag
>>> i think you will have to add a new flag for this, and h264 could use that too
>>>
>>>
>>>        
>> Ok. I will add a new flag. It might be called CODEC_FLAG_COLLECT_FRAME
>>      
> CODEC_FLAG_RETURN_INCOMPLETE_FRAMES
> unless someone has a better idea
>
>
>    

CODEC_FLAG2_RETURN_INCOMPLETE_FRAMES is defined in new patch
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