Change in aspect ratio is ignored

Do you have an example stream? And on which OS with which vouts is this happening ?

ftp://streams.videolan.org/incoming/ticket791/test.ts

WinXP / all vouts

Seems to be a contrib problem (as my private testbuild with contrib-20051020 works fine).

Latest libmpeg2 broken ??

added Component::Build system: Contribs label

I tested this with both svn and 0.8.5, 0.7.2 And I don't ever see an AR change in this sample.

Yep, and this is exactly the problem. You're probably using the latest libmpeg2 installed on your system and thus all VLC versions fail the same way.

If I use VLC-0.8.4 on WinXP (which has older libmpeg2 inside the package) the AR changes into 16:9 together with the scene change (i.e. commercial is 4:3, but CSI is 16:9).

Here is the debug from older libmpeg2-0.4.0 on my Unix box:

Commercial:

    986e S- --- --- - SEQUENCE MPEG2 MP@ML 720x576 chroma 360x288 fps 25 maxBps
1000000 vbv 186368 picture 720x576 display 720x576 pixel 16x15
    9876 SG --- --- - GOP  5:29:48:24
....
   2d05e S- --- --- - SEQUENCE_REPEATED MPEG2 MP@ML 720x576 chroma 360x288 fps 2
5 maxBps 1000000 vbv 186368 picture 720x576 display 720x576 pixel 16x15
   2d066 SG --- --- - GOP  5:29:49:11
....

CSI:

  17e67e S- --- --- - SEQUENCE MPEG2 MP@ML 720x576 chroma 360x288 fps 25 maxBps
1000000 vbv 186368 picture 720x576 display 720x576 pixel 64x45
  17e686 SG --- --- - GOP  5:29:53:19
....
  1b57ea S- --- --- - SEQUENCE_REPEATED MPEG2 MP@ML 720x576 chroma 360x288 fps 2
5 maxBps 1000000 vbv 186368 picture 720x576 display 720x576 pixel 64x45
  1b57f2 SG --- --- - GOP  5:29:54: 6

I.e. there's clearly a new sequence in the MPEG2 stream with changed PAR (64:45)

Weird, seems when I compile libmpeg2-0.4.1 with:

i586-mingw32msvc-gcc (GCC) 3.3.1 (mingw special 20030804-1)

it works.

Does it mean libmpeg2 breaks with latest gcc only???

This is really strange. It seems to be a libmpeg2 bug, I can't find the cause right now. it's possible this won't be fixed before 0.8.6

Finally I've nailed this down:

First, although the contrib Makefile asks for 0.4.1-cvs, seems that the cvs server in fact returns trunk. There is no STATE_SEQUENCE_MODIFIED in 0.4.1-release but the contrib has it.

Second, VLC's implementation of STATE_SEQUENCE_MODIFIED doesn't work. It never gets compilled in, since #ifdef STATE_SEQUENCE_MODIFIED is always FALSE (this is defined inside typedef enum and preprocessor fails to see it) and even if I force it manually, VLC complains about unreferenced/invalid pictures.

Thus the solution for 0.8.6 is: use mpeg2dec-0.4.1-release for contrib. For trunk, the implementation of STATE_SEQUENCE_MODIFIED needs fixing.

New contrib packages uplaoded and installed on altair. Backported in branch

added Status::fixed label

closed

Reopening this one, since trunk now uses libmpeg2-0.5.0

Thus, aspect ratio changes don't work again.

STATE_SEQUENCE_MODIFIED needs fixing as described above.

removed Status::fixed label

reopened

fixing the wrong ifdef it build and linked correctly It then correctly recreate a new vout.

There is 2 error messages when that happens about pictures with an invalid status 6. Not sure if we loose a frame with that

See the following diff for the proper check. We need to see if we need more to avoid the status 6 errors

commit 4ef270f354af9884b5698c9577881704829cc121
Author: Christophe Mutricy <xtophe@videolan.org>
Date:   Thu Jul 17 00:21:02 2008 +0100

    Use the correct test

diff --git a/modules/codec/libmpeg2.c b/modules/codec/libmpeg2.c
index f088638..13ec4c5 100644
--- a/modules/codec/libmpeg2.c
+++ b/modules/codec/libmpeg2.c
@@ -294,9 +294,7 @@ static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_bl$
             p_block->i_buffer = 0;
             break;

-#ifdef STATE_SEQUENCE_MODIFIED
-/* FIXME - the above ifdef is always FALSE, even with libmpeg2-0.5.0
- * Need to improve the implementation to avoid invalid/unref pictures */
+#if MPEG2_RELEASE >= MPEG2_VERSION (0, 5, 0)

         case STATE_SEQUENCE_MODIFIED:
             GetAR( p_dec );

Thanks for fixing the #ifdef.

As for the error messages - they seem to be quite random - sometimes you get invalid status 6, sometimes it's 14038, sometimes the picture has invalid refcount -1 ...

There's definitely something wrong, since when playing the stream with aspect ratio change, I get green squares for a short moment. Seems that GetAR() breaks something related to reference pictures.

The green squares don't appear when I patch the code to ignore STATE_SEQUENCE_MODIFIED - of course no aspect ratio change happens then. So libmpeg2 produces correct frames, the problem is in VLC.

Thus it seems that GetAR() is either not enough for aspect ratio change, or it corrupts pointers to reference pictures. Perhaps we need to save pointers to reference pictures before calling GetAR() and restore them afterwards ?

After some more debugging, seems the problem is caused by the vout respawn via

vout_Destroy and vout_Create.

Seems the newly created vout doesn't inherit proper pointers to reference pictures.

Refs [9a72071a] Use the correct test

changed milestone to %0.9.0 bugs

Change in aspect ratio is ignored

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