[FFmpeg-user] Inserting Seekable Offsets in m4a Audio File

Budgie ajebay at errichel.co.uk
Mon Jul 27 01:13:42 CEST 2015

On 26/07/15 17:56, Carl Eugen Hoyos wrote:
> Budgie <ajebay <at> errichel.co.uk> writes:
>> therefore the seek mechanism of the player I am
>> using does not work.
> Does seeking in the original file works with ffplay?
> (Does it work with "-vn"?)
> If yes, you should probably write to the author of
> the player you are using.
> Carl Eugen
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Hi Carl,
Many thanks for the reply.  I cannot answer your question because I do 
not know how to try "seeking" from a console.

Using smplayer the thumbnail appears on the screen and the progress 
button moves over time.  I can slide the progress button and this 
advances through the file.

I have already taken this problem up with the device manufacturer, Linn. 
  Having sent them a sample of a file which has this problem this was 
their reply:-

"Thank you for providing us with a test file to investigate this issue.

AAC files store data about the media stream they contain within their 
outer MPEG4 container. Seekable AAC files will also provide a collection 
of offsets allowing an AAC decoder to jump to a variety of points in the 
media stream, enabling seeking.

The file you provided us with appears to contain only 1 offset: the 
offset of the start of the audio track within the file (after all the 
metadata). Therefore, there are no further offsets that can allow our 
AAC decoder to safely move to another point within the stream.

As a solution to this, we would recommend using a ripper (e.g. 
dbpoweramp) to transcode the track to another format for use with the DS."

I had assumed the advice they gave was correct and that ffmpeg would be 
the choice if I had to remux.  I do not think transcoding is necessary.

Grateful for your views on Linn's advice and if there is any more I can 

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