[FFmpeg-user] Strange output of ffprobe

Анатолий Коростелев gilgameshfreedom at yandex.ru
Thu Nov 3 12:24:23 EET 2016


Hello!

How did you see missing of the AudioSpecificConfig in the file? It will 
be very useful for me to detect such bad files in the future.


28.10.16 12:09, Анатолий Коростелев пишет:
> > 48000 Hz seems the correct one, so no FFmpeg bug but MediaInfo bug 
> (as a first shot, issue is that there is an ES descriptor without 
> AudioSpecificConfig element in the track header and MediaInfo does not 
> manage correctly this case; note that this may be the reason some 
> players does not play sound).
>
> Under the absence of the AudioSpecificConfig element in the track 
> header do you mean to the absence of the "Format profile" field of the 
> medianfo output? I've looked at the difference between mediainfo 
> output of this bad mp4 file and a good mp4 file and I've found that 
> the good one contains "Format profile":
>
> diff -u mediainfo_output_of_bad_file mediainfo_output_of_good_file:
>
> ...
>
>  Audio
>  ID                                       : 2
> -Format                                   : ER Parametric
> +Format                                   : AAC
>  Format/Info                              : Advanced Audio Codec
> +Format profile                           : LC
>  Codec ID                                 : 40
>  Duration                                 : 22 min 49 s
>  Bit rate mode                            : Constant
>  Bit rate                                 : 128 kb/s
>  Channel(s)                               : 2 channels
> -Sampling rate                            : 7 350 Hz
> -Frame rate                               : 7.178 FPS (1024 spf)
> +Channel positions                        : Front: L R
> +Sampling rate                            : 48.0 kHz
> +Frame rate                               : 46.875 FPS (1024 spf)
>  Compression mode                         : Lossy
>  Stream size                              : 21.0 MiB (38%)
>  Default                                  : Yes
>  Alternate group                          : 1
>
> ...
>
> 28.10.16 0:11, Jerome Martinez пишет:
>> Le 27/10/2016 à 18:06, Анатолий Коростелев a écrit :
>>> Hello!
>>>
>>> Recently I recieved a mp4 for playing. When I tried to play this 
>>> file I didn't hear any sound in some players (in ffplay sound 
>>> worked). When I looked at the metadata of this file (via ffprobe), I 
>>> saw the following:
>>>
>>> [...]
>>>
>>> Then I used mediainfo utility to see the metadata of the file:
>>>
>>> [...]
>>>
>>>
>>> As you can see the "Sampling rate" in mediainfo is 7 350 Hz (it's 
>>> illegal value) 
>>
>> It is not an illegal value, AAC specs authorize it.
>>
>>> while "Sampling rate" in ffprobe is 48000 Hz. I think that the 
>>> problem with the sound of this file has been caused by encoder 
>>> errors/misconfiguration. But it's very strange that ffrobe always 
>>> shows me 48000 Hz Sampling rate. Is this a bug or something else?
>>
>> 48000 Hz seems the correct one, so no FFmpeg bug but MediaInfo bug 
>> (as a first shot, issue is that there is an ES descriptor without 
>> AudioSpecificConfig element in the track header and MediaInfo does 
>> not manage correctly this case; note that this may be the reason some 
>> players does not play sound).
>>
>> Jérôme, developer of MediaInfo.
>>
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>

-- 
С уважением,
Коростелев Анатолий



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