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

[Cédric Schieli]

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