[FFmpeg-user] rewrite tags in a source's PES headers -- How?

[Paul B Mahol]

On Sat, Nov 11, 2023 at 7:29 PM Mark Filipak <markfilipak.imdb at gmail.com>
wrote:

> I'm sorry. I made a DTS mistake...
>
> Here's what I'm doing:
> -bsf:v setts=time_base=1/24000:pts=N*1001:dts=N*1001
>
> Here's the result:
> frame  pts                        dts
>   0        0                       2002 <= should be     0
>   1     3003 <= should be  1001    3003 <= should be  1001
>   2     4004 <= should be  2002    4004 <= should be  2002
>   3     2002 <= should be  3003    5005 <= should be  3003
>   4     5005 <= should be  4004    6006 <= should be  4004
>   5     1001 <= should be  5005    7007 <= should be  5005
>   6     8008 <= should be  6006    8008 <= should be  6006
>   7     9009 <= should be  7007    9009 <= should be  7007
>   8     7007 <= should be  8008   10010 <= should be  8008
>   9    10010 <= should be  9009   11011 <= should be  9009
> 10     6006 <= should be 10010   12012 <= should be 10010
> 11    13013 <= should be 11011   13013 <= should be 11011
> 12    12012 <= should be 12012   14014 <= should be 12012
> 13    14014 <= should be 13013   15015 <= should be 13013
> 14    11011 <= should be 14014   16016 <= should be 14014
> 15    17017 <= should be 15015   17017 <= should be 15015
> 16    18018 <= should be 16016   18018 <= should be 16016
>
> The source video is 'NTSC'-soft.
> Can this be explained?
> Can it be countered?
>
> PTSs in frames 1..5 are +2 +2 -1 +1 -4
> PTSs in frames 6..10 are +2 +2 -1 +1 -4
> PTSs in frames 11..15 are +2 +0 +1 -3 +2
> I'm baffled.
>

N is packet number, and it goes in different order.

Can be confirmed with:

ffmpeg -i <video> -c copy -f framecrc -


>
>
> Hi,
>
> I'm getting some 'wandering' PTSs in the target video.
> The target's PTSs are all in the form 'N*1001', but they go up and down as
> though 'N' goes up and down.
>
>      -bsf:v setts=time_base=1/24000:pts=N*1001:dts=N*1001
>
> The source video is 'NTSC'-soft.
>
> In order to test further, I need a way to change the soft telecine tags in
> the source VOBs. I've
> spent 2 days trying various things.
>
> Is there a way to rewrite tags in a source's PES headers prior to decoding?
>
> Thanks -- Mark.
>
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