Fix for transcoding with vlc 0.9.9a

[Jamin W. Collins]

After upgrading my MythTV box to Debian Lenny, I found that most of my
video files would no longer properly transcode via vlc.  Investigation
seemed to indicate that Debian had removed several of the codecs from
libavcodec that were necessary.  However, the necessary codecs were
present in the Ubuntu archives.  So, I converted my MythTV box to
Ubuntu's latest release Jaunty (9.04).  However, the video files still
would not transcode via vlc.

Starting vlc with the "-v2" command line option resulted in the
following error when trying to play any of the problematic files:

[00000482] [Media: mvpmc] avcodec encoder warning: MPEG1/2 does not
support 2997/100 fps
  (mpeg2video@0x8242240)
[00000482] [Media: mvpmc] avcodec encoder error: cannot open encoder
[00000482] [Media: mvpmc] main encoder warning: no encoder module
matching "ffmpeg" could be loaded
[00000482] [Media: mvpmc] main encoder debug: TIMER module_Need() :
3.559 ms - Total 3.559 ms / 1 intvls (Avg 3.559 ms)
[00000392] [Media: mvpmc] stream_out_transcode stream out error: cannot
find video encoder (module:ffmpeg fourcc:mp2v)

The first two lines of the above output were the key.  While a frame
rate of 29.970 is technically more correct for NTSC output, the
transcoding codec does not support it.  Modifying the dongle
(src/vlc_control.c line 665) to use a frame rate of 30.000 instead works
perfectly.

Patch attached.

--
Jamin W. Collins

diff --git a/src/vlc_control.c b/src/vlc_control.c
index 9307ffc..7c6b29c 100644
--- a/src/vlc_control.c
+++ b/src/vlc_control.c
@@ -662,7 +662,8 @@ char* vlc_get_video_transcode()
  fps = "25.0000";
  } else {
  canvas_height = "480";
- fps = "29.9700";
+ //fps = "29.9700";
+ fps = "30.0000";
  }
 
  /* bitrate settings */

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[haapi]

Jamin W. Collins wrote:

> After upgrading my MythTV box to Debian Lenny, I found that most of my
> video files would no longer properly transcode via vlc.  Investigation
> seemed to indicate that Debian had removed several of the codecs from
> libavcodec that were necessary.  However, the necessary codecs were
> present in the Ubuntu archives.  So, I converted my MythTV box to
> Ubuntu's latest release Jaunty (9.04).  However, the video files still
> would not transcode via vlc.
>
> Starting vlc with the "-v2" command line option resulted in the
> following error when trying to play any of the problematic files:
>
> [00000482] [Media: mvpmc] avcodec encoder warning: MPEG1/2 does not
> support 2997/100 fps
>  (mpeg2video@0x8242240)
> [00000482] [Media: mvpmc] avcodec encoder error: cannot open encoder
> [00000482] [Media: mvpmc] main encoder warning: no encoder module
> matching "ffmpeg" could be loaded
> [00000482] [Media: mvpmc] main encoder debug: TIMER module_Need() :
> 3.559 ms - Total 3.559 ms / 1 intvls (Avg 3.559 ms)
> [00000392] [Media: mvpmc] stream_out_transcode stream out error: cannot
> find video encoder (module:ffmpeg fourcc:mp2v)
>
> The first two lines of the above output were the key.  While a frame
> rate of 29.970 is technically more correct for NTSC output, the
> transcoding codec does not support it.  Modifying the dongle
> (src/vlc_control.c line 665) to use a frame rate of 30.000 instead works
> perfectly.
>
> Patch attached.
>
>

Any downside of this patch for the mvpmc code?

Pity vlc doesn't have a param to lock/fake the framerate.  It has enough
similar parameters, after all.
--
Clay Haapala

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[Jamin W. Collins]

Clay Haapala wrote:
>
> Any downside of this patch for the mvpmc code?

I haven't found any downsides yet.  Been running on the modified code
since I submitted the patch to the list.

--
Jamin W. Collins

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[Simon Hyde]

On Mon, 11 May 2009, Jamin W. Collins wrote:

> Clay Haapala wrote:
>>
>> Any downside of this patch for the mvpmc code?
>
> I haven't found any downsides yet.  Been running on the modified code
> since I submitted the patch to the list.

Have you been able to test this against an old (v0.8) version of VLC? I
live in a PAL country, and my TV doesn't support NTSC signals. If it is
confirmed as still working with v0.8 I'd be happy to push this patch to
the main repo.

Thanks,

Simon

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[Jamin W. Collins]

Simon Hyde wrote:
>
> Have you been able to test this against an old (v0.8) version of VLC? I
> live in a PAL country, and my TV doesn't support NTSC signals. If it is
> confirmed as still working with v0.8 I'd be happy to push this patch to
> the main repo.

I'm currently in the process of packing everything up in preparation to
move across the country on the 22nd.  I doubt I'll be able to get to it
before the move, but if it's still outstanding after the move, I'll see
what I can do.

--
Jamin W. Collins

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[brn5336]

How would I apply this patch?  I am a noob when it comes to this.   I cannot play .AVI files using MythTV/Mvpmc/Ubuntu 8.10. Can I just download the latest mvpmc dongle from the list?

Jamin W. Collins wrote:

Patch attached.

--
Jamin W. Collins

diff --git a/src/vlc_control.c b/src/vlc_control.c
index 9307ffc..7c6b29c 100644
--- a/src/vlc_control.c
+++ b/src/vlc_control.c
@@ -662,7 +662,8 @@ char* vlc_get_video_transcode()
  fps = "25.0000";
  } else {
  canvas_height = "480";
- fps = "29.9700";
+ //fps = "29.9700";
+ fps = "30.0000";
  }
 
  /* bitrate settings */

[Brett A. Taylor]

Hello,

I know this dates back to April. I found a workaround with a chrooted
vlc on ubuntu that I posted. But after switching to from Ubuntu to
Fedora, I'm trying to get this working correctly with the patch from
Jamin noted below.

Does anyone have an unofficial build that include this patch? I checked
the nightlies and I noticed that this hasn't even been put into git.

(Mostly, I'm just being lazy and trying to avoid rebuilding the
toolchain and mvpmc to make a single line code change.)


Thanks
Brett

On 04/25/2009 01:57 PM, Jamin W. Collins wrote:

> After upgrading my MythTV box to Debian Lenny, I found that most of my
> video files would no longer properly transcode via vlc. Investigation
> seemed to indicate that Debian had removed several of the codecs from
> libavcodec that were necessary. However, the necessary codecs were
> present in the Ubuntu archives. So, I converted my MythTV box to
> Ubuntu's latest release Jaunty (9.04). However, the video files still
> would not transcode via vlc.
>
> Starting vlc with the "-v2" command line option resulted in the
> following error when trying to play any of the problematic files:
>
> [00000482] [Media: mvpmc] avcodec encoder warning: MPEG1/2 does not
> support 2997/100 fps
> (mpeg2video@0x8242240)
> [00000482] [Media: mvpmc] avcodec encoder error: cannot open encoder
> [00000482] [Media: mvpmc] main encoder warning: no encoder module
> matching "ffmpeg" could be loaded
> [00000482] [Media: mvpmc] main encoder debug: TIMER module_Need() :
> 3.559 ms - Total 3.559 ms / 1 intvls (Avg 3.559 ms)
> [00000392] [Media: mvpmc] stream_out_transcode stream out error: cannot
> find video encoder (module:ffmpeg fourcc:mp2v)
>
> The first two lines of the above output were the key. While a frame rate
> of 29.970 is technically more correct for NTSC output, the transcoding
> codec does not support it. Modifying the dongle (src/vlc_control.c line
> 665) to use a frame rate of 30.000 instead works perfectly.
>
> Patch attached.
>
>
>
> ------------------------------------------------------------------------------
> Crystal Reports- New Free Runtime and 30 Day Trial
> Check out the new simplified licensign option that enables unlimited
> royalty-free distribution of the report engine for externally facing
> server and web deployment.
> http://p.sf.net/sfu/businessobjects
>
>
>
> _______________________________________________
> Mvpmc-devel mailing list
> Mvpmc-devel@...
> https://lists.sourceforge.net/lists/listinfo/mvpmc-devel

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