[FFmpeg-devel] [RFC] avformat/mxfenc: stop encoding if unfilled video packet

[Tobias Rapp]

On 19.09.2015 22:49, Tomas Härdin wrote:
> On Wed, 2015-09-16 at 14:33 +0200, Tobias Rapp wrote:
>> Hi,
>>
>> attached patch fixes ticket #4759 but I guess it is a bit too hasty to
>> always abort transcoding if a single frame cannot be written. I guess it
>> would be better to check for some "exit_on_error" like flag set but
>> couldn't find out how to achieve that.
>>
>> Any comments would be appreciated.
>>
>> Regards,
>> Tobias
>
>
>>  From 7d6f8de2a411817c970a19d8766e69b6eb604132 Mon Sep 17 00:00:00 2001
>> From: Tobias Rapp <t.rapp at noa-audio.com>
>> Date: Mon, 14 Sep 2015 12:06:22 +0200
>> Subject: [PATCH] avformat/mxfenc: stop encoding if unfilled video packet
>>   occurs
>>
>> Fixes ticket #4759.
>> ---
>>   libavformat/mxfenc.c | 14 +++++++++-----
>>   1 file changed, 9 insertions(+), 5 deletions(-)
>>
[...]
>
> Is this really better than not writing anything?
>
> /Tomas

(Sorry for the long delay in answering, I was caught by a flu last week.)

I want to transcode thousands of files and want to get some indication 
from ffmpeg if the transcoding has been successful (all frames have been 
transcoded) or not. Currently I am using the process exit code to verify 
that.

There are two different user stories when using ffmpeg:
a) "process the input data and exit with error as early as possible in 
case of errors/problems"
b) "process the input data and avoid exit with error as long as possible 
in case of error/problems"

If I understand correctly I can basically switch between (a) and (b) 
mode by passing the "-xerror" option to ffmpeg or not. So my plan is to 
transcode all my files with "-xerror" and assume that >99% of the files 
will pass. The small amount of failing ones can then be analyzed for 
problems manually and possibly have a re-run without "-xerror".

Unfortunately the "-xerror" option affects only ffmpeg but not the 
libraries, so I cannot use it do decide if "mxf_write_packet" should 
return with an error when the video packet size doesn't match the CBR 
constraints.

Regards,
Tobias