1. ffmpeg
  2. Commit 438f3ef8214ddc3bc3f2c25328c34065df48d4e6
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RV20: try keeping aspect during resolution changes.

Resolution changes are usually only used to scale with
network bandwidth, the (full) resolution specified in the
RM header really is authoritative.
While I am not sure this is the best solution, it is a
conservative approach that still should fix the most
common cases.
In particular, it fixes aspect with the sample from trac
issue #785 (in MPlayer, ffplay seems to just ignore
sample aspect changes in mid-playback).

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

Reimar Döffinger authored on 2012/04/09 21:21:01
Showing 1 changed files
libavcodec/rv10.c
History View file @ 438f3ef
... ... 
@@ -371,10 +371,19 @@ static int rv20_decode_picture_header(RVDecContext *rv)
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             new_h= s->orig_height;
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         }
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         if(new_w != s->width || new_h != s->height){
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+            AVRational old_aspect = s->avctx->sample_aspect_ratio;
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             av_log(s->avctx, AV_LOG_DEBUG, "attempting to change resolution to %dx%d\n", new_w, new_h);
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             if (av_image_check_size(new_w, new_h, 0, s->avctx) < 0)
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                 return -1;
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             ff_MPV_common_end(s);
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+
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+            // attempt to keep aspect during typical resolution switches
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+            if (!old_aspect.num)
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+                old_aspect = (AVRational){1, 1};
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+            if (2 * new_w * s->height == new_h * s->width)
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+                s->avctx->sample_aspect_ratio = av_mul_q(old_aspect, (AVRational){2, 1});
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+            if (new_w * s->height == 2 * new_h * s->width)
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+                s->avctx->sample_aspect_ratio = av_mul_q(old_aspect, (AVRational){1, 2});
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             avcodec_set_dimensions(s->avctx, new_w, new_h);
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             s->width  = new_w;
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             s->height = new_h;