Problem with transcoding some HD programmes

[dinkypumpkin]

On 27/05/2012 22:15, Shevek wrote:
> I got this error from ffmpeg:
>
> [mp4 @ 044F5700] Application provided invalid, non monotonically increasing dts
> to muxer in stream 1: 86800368>= 86642688
>
> which stopped ffmpeg and left me with the flv file.
>
> I updated to the latest build of ffmpeg from Zeranoe and used --force
> to attempt to transcode the already downloaded flv and now I get
> repeated warnings from ffmpeg:
>
> [mp4 @ 01d4ba60] pts has no value
> DTS 1839840, next:1843160000 st:0 invalid dropping
> PTS 1840040, next:1843160000 invalid dropping st:0
> DTS 1839872, next:1843199122 st:1 invalid dropping
> PTS 1839872, next:1843199122 invalid dropping st:1
>
> The transcoding did finish and then get_iplayer successfully tagged the MP4
>
> Any pointers?

There have been some notable changes in this area in the 
recently-released ffmpeg 0.11.  Some patches to address the 
non-monotonic timestamps warnings have been committed over the last few 
months.  Now that a new branch has been cut for 0.11, those patches are 
incorporated into release builds.

The repeated warnings you saw indicate that ffmpeg is skipping packets 
with "backwards" timestamps when re-muxing H264/AAC streams to MP4 
container.  Similar errors when re-muxing MP3 streams have also 
disappeared with ffmpeg 0.11.  For the MP3 case I expected to see 
warnings like those above, but I didn't and I'm not sure why.  Still, it 
worked.

In the distant future these changes mean we can eventually drop mplayer 
as a get_iplayer dependency.  AFAICT, mplayer is used to re-mux MP3 
streams solely to avoid the stream of "non monotonically increasing..." 
messages thrown out by ffmpeg.  But it will take a long time for distros 
to catch up to ffmpeg 0.11, and who knows what libav will do.

If you're feeling generous, it would be good to know how you get on with 
the latest ffmpeg on Windows.  It would be worth knowing whether or not 
your MP4 re-muxing works OK even though you might see a lot of those 
warning messages.  If that turns out to be the case, it might be a good 
idea for me to update the windows installer config so everyone can 
update.  Zeranoe stopped doing release builds of ffmpeg a long time, but 
there is a build taken from the commit where ffmpeg 0.11 was branched, 
which should fill the bill.

I'm also thinking that those warning messages could be suppressed by 
get_iplayer unless --verbose is specified, for example, but that might 
be something that should be considered as part of a more global overhaul 
of get_iplayer logging.  For another time.