[MEncoder-users] How to Change FPS on a Broken TS Stream?

[Bill Adams]

Thanks all for your suggestions. Unfortunately it looks like getatsc 
does not do the right thing -- I will cover that below but want to 
answer some questions first...

A link to a sample bad ts stream is here: 
http://evilbill.org/static/Bad-FPS.ts 
Again, this is the opening to Lost season 2 episode 1 so be warned it is 
be a spoiler for anyone who has not already seen all of season one.

When I run:
~/tmp/dtvstream-linux-1.1/dtvstream -i Bad-FPS.ts -o Tmp.mpg -v -d -a 
1000000000000
I see many, many lines of "Waiting for a free buffer." but nothing else 
that stands out to me.

The reason that I want to encode the material to 1280x720 is that is the 
native resolution of my projector. The scale=1280:720 is unnecessary for 
the ABC material as it is already that resolution but the OPB/PBS 
Secrets of the Dead stream is 1080i so I am down-sampling it and 
deinterlacing it to the native resolution of my projector. This is why I 
do not use the format=dvd option. I tried that option on the bad stream 
and it did not help.

 > Do you know that you are getting good reception of ABC?

My reception according to "dtvsignal 43" (ABC in my area Portland OR) 
reports 94-98%.

I have some NBC streams from Conan. They are 1920x1080 and transcode 
fine with e.g.:
mencoder -oac copy -ovc lavc -lavcopts 
vcodec=mpeg2video:vqscale=4:dia=4:keyint=20 -vf pp=fp -of mpeg -o 
Test.mpg Conan-OBrien-Tue.ts

As it turns out, captures with a stock getatsc from FOX exhibit the same 
problem where the FPS is wrong. I don't  know why I never  noticed this.

 > The strange thing about this capture is that there are many video
 > packets full of zeros. There are also no null packets - how exactly did
 > you capture it?

I use a version of getatsc (dvb-atsc-tools 
http://www.pchdtv.com/downloads.html) that I hacked to filter out 
specific PIDs. I have not put this to the outside world (yet). The 
Bad-FPS.ts referenced above was created with the noop tools 
atscut/xtscut. The hack that I did writes all packets to the disks 
except the ones for the PIDs of the sub-channels I do not want (this was 
before I realized that mencoder could filter on PIDs too). If anyone 
wants, I can email my version of getatsc.c. As it turns out, the stock 
version of getatsc has the same problem where mencoder reports a funny 
fps for full stream captures. My guess is that something needs to be 
filtered from the stream that is not getting filtered.

A question: How did you find these video packets full of zeros? Is there 
an easy way I can filter them without breaking the video stream? (Or 
RTFM link)? I have a strange feeling that if I get rid of those 
packets/video frames (or fix getatsc to properly detect null packets) 
the problem I see will go away.

Thanks again everyone.

b.