get_iplayer Download Olympics In Chunks Tutorial

[MS]

On 09/08/12 11:05, Jimmy Aitken wrote:
> On Tuesday, 7 August 2012 at 16:46, MS wrote:
>> Hi all,
>>
>> Matthew Kerle emailed me directly asking for help to download
>> Olympic event sessions in chunks. I decided to write a tutorial for
>> him and for the list.
>>
>
> That has been a great help.  It clarifies lots of things in one
> place. I do have one question.  My part 2 of the opening ceremony, no
> matter what start seek point I use has an audio skew of about 2
> seconds.  Is there a way of moving the audio around so that it's
> correct.  I've tried using the its offset command, but it seems to
> only work with a 2nd audio stream, and not with the flv file that it
> downloaded.

The answer is yes, but the problem may be (will be?) getting it 
perfectly in sync.

You could try using ffmpeg to convert to .mp4 first and then using that 
file with the offset command. Or outputting the video and audio to 
separate files and joining them with an offset.

I just remembered that Avidemux has an audio offset - I just checked and 
it has a 'shift' audio feature in the main interface which accepts 
positive and negative values, you could load you 2nd chunk, set video 
and audio to copy, output format to MP4 and play around with the audio 
shift values. 'Shift' takes a millisec value so getting it exactly right 
could take a long while.

In VLC's extended settings the syncronization tab allows you to adjust 
audio sync (again pos/neg) - that may be your best bet for finding the 
exact millsecs adjustment you need.

I've downloaded in excess of 20 chunks, of various things, and never 
once had an audio sync problem, but I haven't tried the opening ceremony 
at all.

Will you reply with the 2nd chunk command you used and I'll try and 
reproduce the problem and have a play around too.

dinkypumpkin wrote earlier that he'd already made a "proper edit of the 
opening ceremony", maybe he'd consider making that available to the list?

HTH.