[FFmpeg-user] Excessive reporting with -report option in latest FFMPEG builds

[Nicolas George]

L'octidi 18 messidor, an CCXX, Erling Groenlund a écrit :
> Since this mail forum is intended for general user questions, I am
> posting my question here - but as I am new to the mail forum and
> unsure how it works, please forgive me if I am posting this
> incorrectly or in the wrong place!

This mail is perfectly fine. Just be sure not to top-post (look it up if
necessary) when you reply.

> I use the Windows builds of FFMPEG and have made a front end
> application which issues a command string of the form:
> 
> 'ffmpeg -report -y -i concat:"data0001.ts|data0002.ts" -vol 456
> -deinterlace -vtag DIVX -f avi -vcodec mpeg4  -aspect 16:9 -s
> 720x576 -b:v 2000000 -acodec libmp3lame  -ab 192000 -ar 48000 -ac 2
> -async 48000 <output file>'
> 
> The front end regularly polls the last line of the log file created
> with the -report option to track the progress of video conversions.
> This has worked very well with previous builds, where the last line
> would nearly always read something of the form
> 
> 'frame=96926 fps=189 q=4.4 size= 1039951kB time=01:04:38.40
> bitrate=2196.6kbits/s'
> 
> making it easy to track the current progress of a conversion.
> 
> However, when using the most recent Zerrano builds (from 2012-06-08
> git-718607b and on), I have noticed that these 'progress lines' are
> interspersed by a very high number of nearly identical lines of the
> form
> 
> '[mpegts @ 0235e420] first_dts 4802459367 not matching first dts
> 4812529287 in que'
> 
> and consequently the last line now only very rarely contains any
> progress information, and the log files easily grow to many MBs in
> size.
> 
> It should be noted that the actual conversion still works fine and
> yields excellent results, and the problem seems to be merely a
> reporting issue with the latest builds.
> 
> Is there any way to modify the command line so I can get rid of
> these (rather superfluous) error lines in the log file while still
> being able to retrieve the progress information?

In short: no. The -report option is for bug reports, and as such must
include all possibly relevant information. A warning produced by the
encoding process is clearly possibly relevant, so it must be there.

But that does not mean you are stuck.

First, if the encoding process works well, these warning may be phony; at
the very least they need investigating. Can you reproduce the problem with a
small file and attach it to a new Trac ticket, along with the corresponding
-report file?

Second, you should should consider using a more reliable method of tracking
the progress of ffmpeg than parsing the information output of ffmpeg,
especially keeping only one line at random. The information output is meant
for humans, not programs, and developers can decide to change its format at
any time, breaking your program.

I can suggest, right now, "-r 1 -an -f framecrc progress.crc", it will write
one line for each second worth of video encoded. In the longest run, maybe
you should open another Trac ticket, of the "enhancement/wish"
type/priority, requesting a script-friendly progress output.

Regards,

-- 
  Nicolas George
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