get_iplayer Download Olympics In Chunks Tutorial

[dinkypumpkin]

On 09/08/2012 18:35, MS wrote:
> Ok Jimmy - I can confirm that I can reproduce your problem as reported.
>
> This command downloaded the chunk from your starting position of 9700 to
> the end (13856.68) and the .mp4.flv file plays with no audio sync problems.
>
> ./get_iplayer --pid p00w2r5c --start 9700 -o /output/ --force
> Download renamed as: partial.mp4.flv
>
> However when the ffmpeg command below is run, to output the speech,
> ffmpeg produces a .mp4 file with the audio out of sync.

This might be a case where it's better to put -ss before the input file 
in your ffmpeg command, i.e., skip then decode rather than decode then 
skip (-ss after input file).  It's not very scientific, but I've noticed 
that when there is a noticeable offset between the start times of the 
video and audio tracks at the beginning of the file (often the case with 
--start), instructing ffmpeg to seek ahead to where both audio and video 
streams are present before decoding seems to help. Of course, the 
audio/video offset in the output file shouldn't necessarily be a 
problem, but some media players can't deal with it.  Totem (aka GNOME 
Movie Player) is one of those, but VLC usually works OK.