[FFmpeg-cvslog] r18421 - trunk/libavcodec/pngdec.c

[Justin Ruggles]

C?dric Schieli wrote:
> 2009/4/10 stefano <subversion at mplayerhq.hu>:
>> Author: stefano
>> Date: Fri Apr 10 19:16:19 2009
>> New Revision: 18421
>>
>> Log:
>> Add support to CorePNG P-frames.
>>
>> Patch by Thilo Borgmann thilo DOT borgmann A googlemail com.
>>
>> Modified:
>>   trunk/libavcodec/pngdec.c
>>
>> Modified: trunk/libavcodec/pngdec.c
>> ==============================================================================
>> --- trunk/libavcodec/pngdec.c   Fri Apr 10 19:12:36 2009        (r18420)
>> +++ trunk/libavcodec/pngdec.c   Fri Apr 10 19:16:19 2009        (r18421)
>> @@ -37,7 +37,8 @@ typedef struct PNGDecContext {
>>     const uint8_t *bytestream;
>>     const uint8_t *bytestream_start;
>>     const uint8_t *bytestream_end;
>> -    AVFrame picture;
>> +    AVFrame picture1, picture2;
>> +    AVFrame *current_picture, *last_picture;
>>
>>     int state;
>>     int width, height;
>> @@ -385,10 +386,14 @@ static int decode_frame(AVCodecContext *
>>     int buf_size = avpkt->size;
>>     PNGDecContext * const s = avctx->priv_data;
>>     AVFrame *picture = data;
>> -    AVFrame * const p= &s->picture;
>> +    AVFrame *p;
>>     uint32_t tag, length;
>>     int ret, crc;
>>
>> +    FFSWAP(AVFrame *, s->current_picture, s->last_picture);
>> +    avctx->coded_frame= s->current_picture;
>> +    p = s->current_picture;
>> +
>>     s->bytestream_start=
>>     s->bytestream= buf;
>>     s->bytestream_end= buf + buf_size;
>> @@ -584,7 +589,24 @@ static int decode_frame(AVCodecContext *
>>         }
>>     }
>>  exit_loop:
>> -    *picture= s->picture;
>> +     /* handle p-frames only if a predecessor frame is available */
>> +     if(s->last_picture->data[0] != NULL) {
>> +         if(!(avpkt->flags & PKT_FLAG_KEY)) {
>> +            int i, j;
>> +            uint8_t *pd = s->current_picture->data[0];
>> +            uint8_t *pd_last = s->last_picture->data[0];
>> +
>> +            for(j=0; j < s->height; j++) {
>> +                for(i=0; i < s->width * s->bpp; i++) {
>> +                    pd[i] += pd_last[i];
>> +                }
>> +                pd += s->image_linesize;
>> +                pd_last += s->image_linesize;
>> +            }
>> +        }
>> +    }
>> +
>> +    *picture= *s->current_picture;
>>     *data_size = sizeof(AVFrame);
>>
>>     ret = s->bytestream - s->bytestream_start;
>> @@ -602,8 +624,10 @@ static int decode_frame(AVCodecContext *
>>  static av_cold int png_dec_init(AVCodecContext *avctx){
>>     PNGDecContext *s = avctx->priv_data;
>>
>> -    avcodec_get_frame_defaults(&s->picture);
>> -    avctx->coded_frame= &s->picture;
>> +    s->current_picture = &s->picture1;
>> +    s->last_picture = &s->picture2;
>> +    avcodec_get_frame_defaults(&s->picture1);
>> +    avcodec_get_frame_defaults(&s->picture2);
>>     dsputil_init(&s->dsp, avctx);
>>
>>     return 0;
> 
> I didn't dig into it right now, but this commit breaks image2 png
> sequences. Each frame gets darker than the preceding one, and some
> noise also appears.
> To reproduce : ffmpeg -loop_input -i any.png -vframes 300 out.avi

Unable to reproduce here. It works fine for me using the command you gave.

-Justin