Re: [linux-dvb] dvb mpeg2?

Re: [linux-dvb] dvb mpeg2?

[Tobias Stoeber]

Tim Farrington schrieb:
> Can you please give me some guidance as to how to discover
> what format is output from the v4l-dvb driver.
> 
> The DVB-T standard is, as I understand it, MPEG2,
> however with kaffeine, me-tv, mplayer if I record to a file,
> (dump from the raw data stream),
> it appears to be stored as a MPEG1 file.
> If I use GOPchop, it will not open any of these files,
> as it will only open MPEG2 files.

Well if I remember it right, a DVB stream (in MPEG2) is MPEG2-TS and 
GOPchop will handle MPEG2-PS!

Cheers, Tobias


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Re: [linux-dvb] dvb mpeg2?

[Tim Farrington]

Tobias Stoeber wrote:
> Tim Farrington schrieb:
>> Can you please give me some guidance as to how to discover
>> what format is output from the v4l-dvb driver.
>>
>> The DVB-T standard is, as I understand it, MPEG2,
>> however with kaffeine, me-tv, mplayer if I record to a file,
>> (dump from the raw data stream),
>> it appears to be stored as a MPEG1 file.
>> If I use GOPchop, it will not open any of these files,
>> as it will only open MPEG2 files.
>
> Well if I remember it right, a DVB stream (in MPEG2) is MPEG2-TS and 
> GOPchop will handle MPEG2-PS!
>
> Cheers, Tobias
>
Hi Tobias,
Do you mean GOPchop won't open MPEG2-TS?

What I'm after is some tool/means which will accurately display a format 
descriptor for
a MPEG(x) file/stream.

MPEG2-TS is what is supposed to be the format, but how can I discover if 
it really is?

Regards,
Tim Farrington

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Re: [linux-dvb] dvb mpeg2?

[Tobias Stoeber]

Hi Tim,

Tim Farrington schrieb:
> Do you mean GOPchop won't open MPEG2-TS?

Yes, that's what I suppose. That it won't open MPEG2-TS.

> What I'm after is some tool/means which will accurately display a format 
> descriptor for
> a MPEG(x) file/stream.
> 
> MPEG2-TS is what is supposed to be the format, but how can I discover if 
> it really is?

Well, you could possibly try

mplayer -identify -vo null -ao null file.mpg

Cheers, Tobias



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Re: [linux-dvb] dvb mpeg2?

[Nico Sabbi]

On Thursday 24 July 2008 13:13:51 Tim Farrington wrote:
> Tobias Stoeber wrote:
> > Tim Farrington schrieb:
> >> Can you please give me some guidance as to how to discover
> >> what format is output from the v4l-dvb driver.
> >>
> >> The DVB-T standard is, as I understand it, MPEG2,
> >> however with kaffeine, me-tv, mplayer if I record to a file,
> >> (dump from the raw data stream),
> >> it appears to be stored as a MPEG1 file.
> >> If I use GOPchop, it will not open any of these files,
> >> as it will only open MPEG2 files.
> >
> > Well if I remember it right, a DVB stream (in MPEG2) is MPEG2-TS
> > and GOPchop will handle MPEG2-PS!
> >
> > Cheers, Tobias
>
> Hi Tobias,
> Do you mean GOPchop won't open MPEG2-TS?
>
> What I'm after is some tool/means which will accurately display a
> format descriptor for
> a MPEG(x) file/stream.
>
> MPEG2-TS is what is supposed to be the format, but how can I
> discover if it really is?
>
> Regards,
> Tim Farrington
>

www.avidemux.org will open it.
file file.ts should say something about it

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Re: [linux-dvb] dvb mpeg2?

[Tobias Stoeber]

Just a short correction to my last mail ...

mplayer -identify -vo null -ao null -frames 0 file.mpg

should be better ;) Doesn't try to display any frames.

Cheers.

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Re: [linux-dvb] dvb mpeg2?

[Stephen Rowles]

> MPEG2-TS is what is supposed to be the format, but how can I discover if
> it really is?
>
> Regards,
> Tim Farrington

I use mplayer e.g.

mplayer -identify 06-29_20_00_Top_Gear.ts -frames 0 -vo null -nosound

Which after lots of output finally gives the following and you can see at
the bottom in my case that this is a Mpeg 1/2 video, which is encapsulated
inside an mpegts file (ID_DEMUXER line below). For reference I recorded
this file from my DVB-T USB stick using mplayer with the -dumpstream
command.

VIDEO:  MPEG2  720x576  (aspect 3)  25.000 fps  6500.0 kbps (812.5 kbyte/s)
ID_FILENAME=06-29_20_00_Top_Gear.ts
ID_DEMUXER=mpegts
ID_VIDEO_FORMAT=0x10000002
ID_VIDEO_BITRATE=6500000
ID_VIDEO_WIDTH=720
ID_VIDEO_HEIGHT=576
ID_VIDEO_FPS=25.000
ID_VIDEO_ASPECT=0.0000
ID_LENGTH=2074.19
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 720 x 576 (preferred colorspace: Mpeg PES)
VDec: using Mpeg PES as output csp (no 0)
Movie-Aspect is undefined - no prescaling applied.
VO: [null] 720x576 => 720x576 Mpeg PES
Selected video codec: [mpegpes] vfm: mpegpes (MPEG-PES output (.mpg or
DXR3/IVTV/DVB card))
==========================================================================
ID_VIDEO_CODEC=mpegpes
Audio: no sound
Starting playback...


Exiting... (End of file)



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Re: [linux-dvb] dvb mpeg2?

[Tim Farrington]

Nico Sabbi wrote:
> On Thursday 24 July 2008 13:13:51 Tim Farrington wrote:
>   
>> Tobias Stoeber wrote:
>>     
>>> Tim Farrington schrieb:
>>>       
>>>> Can you please give me some guidance as to how to discover
>>>> what format is output from the v4l-dvb driver.
>>>>
>>>> The DVB-T standard is, as I understand it, MPEG2,
>>>> however with kaffeine, me-tv, mplayer if I record to a file,
>>>> (dump from the raw data stream),
>>>> it appears to be stored as a MPEG1 file.
>>>> If I use GOPchop, it will not open any of these files,
>>>> as it will only open MPEG2 files.
>>>>         
>>> Well if I remember it right, a DVB stream (in MPEG2) is MPEG2-TS
>>> and GOPchop will handle MPEG2-PS!
>>>
>>> Cheers, Tobias
>>>       
>> Hi Tobias,
>> Do you mean GOPchop won't open MPEG2-TS?
>>
>> What I'm after is some tool/means which will accurately display a
>> format descriptor for
>> a MPEG(x) file/stream.
>>
>> MPEG2-TS is what is supposed to be the format, but how can I
>> discover if it really is?
>>
>> Regards,
>> Tim Farrington
>>
>>     
>
> www.avidemux.org will open it.
> file file.ts should say something about it
>
> _______________________________________________
> linux-dvb mailing list
> linux-dvb@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
>
>   
Hi Nico,
I was a huge fan of avidemux until about 2 hours ago when I discovered
that editing a file caused all sorts of grief with a/v sync.
Its doc's tell me to send the file through Projectx first, etc

Hence, I was attracted to gopchop.

All I would like is an mpeg gui editor which can simply edit a file 
dumped from
my dvb stream. I've tried many such as Cinerra (I think that's its name),
but this help from Tobias may give me a clue as to why many of them 
won't open
these files - they are MPEG2-TS and the apps perhaps need MPEG2-PS

Regards,
Tim Farrington

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Re: [linux-dvb] dvb mpeg2?

[Nico Sabbi]

On Thursday 24 July 2008 14:02:17 you wrote:

>
> Hi Nico,
> I was a huge fan of avidemux until about 2 hours ago when I
> discovered that editing a file caused all sorts of grief with a/v
> sync. Its doc's tell me to send the file through Projectx first,
> etc

avidemux is still the way to go: in order to fix the synchrony just
run mplayer on the file beforehand taking notice of the value of
"rc" on the status line when the delay between audio and video
drops to 0, then insert that value in the delay field of avidemux
(-N)

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Re: [linux-dvb] dvb mpeg2?

[Tim Farrington]

Hi all,

Got there:

Filetype is MPEG2-TS (generic PES Container)

Need to use mplayer, projectx to ascertain this.

This is what I have just done to achieve an a/v sync perfect, edited, 
recorded dvb file:

1. Run file through project-x; divides files into *.mp2 (MPEG audio 
stream), *.m2v (video stream),
   (plus for HDTV *.ac3 (for Dolby Digital aka AC3 stream))
projectx rec-file.mpeg => rec-file.m2v rec-file.mp2

2. Run *.mp2 *.m2v through mplex to recombine into PS format
mplex -f 8 -o rec-file-a.mpeg rec-file.m2v rec-file.mp2 => rec-file-a.mpeg

3. Edit resultant file with avidemux on I-Frames while retaining a/v 
sync => rec-file-a-a.mpeg

And it produces a perfect new file!

My huge thanks to you all for your assistance.

Regards,
Tim Farrington

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Re: [linux-dvb] dvb mpeg2?

[Nico Sabbi]

On Thursday 24 July 2008 15:43:28 Tim Farrington wrote:
> Hi all,
>
> Got there:
>
> Filetype is MPEG2-TS (generic PES Container)
>
> Need to use mplayer, projectx to ascertain this.
>
> This is what I have just done to achieve an a/v sync perfect,
> edited, recorded dvb file:
>
> 1. Run file through project-x; divides files into *.mp2 (MPEG audio
> stream), *.m2v (video stream),
>    (plus for HDTV *.ac3 (for Dolby Digital aka AC3 stream))
> projectx rec-file.mpeg => rec-file.m2v rec-file.mp2
>
> 2. Run *.mp2 *.m2v through mplex to recombine into PS format
> mplex -f 8 -o rec-file-a.mpeg rec-file.m2v rec-file.mp2 =>
> rec-file-a.mpeg
>
> 3. Edit resultant file with avidemux on I-Frames while retaining
> a/v sync => rec-file-a-a.mpeg
>
> And it produces a perfect new file!
>
> My huge thanks to you all for your assistance.
>
> Regards,
> Tim Farrington


be aware that demuxing the TS in its elementary streams implicitly
drops all timestamps (that are recorded in the PES headers), thus
recombining the audio and video streams will produce a desynchronized
output, unless you are lucky.
There simply aren't enough informations to keep synchrony without
timestamps. With your method if a stream is corrupt
you will likely see a desynchronization from the first breakage
onward, while working on the TS the muxer has a chance to recover

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Re: [linux-dvb] dvb mpeg2?

[Nico Sabbi]

On Thursday 24 July 2008 15:57:06 Nico Sabbi wrote:

>
> be aware that demuxing the TS in its elementary streams implicitly
> drops all timestamps (that are recorded in the PES headers), thus
> recombining the audio and video streams will produce a
> desynchronized output, unless you are lucky.
> There simply aren't enough informations to keep synchrony without
> timestamps. With your method if a stream is corrupt
> you will likely see a desynchronization from the first breakage
> onward, while working on the TS the muxer has a chance to recover
>

BTW, although mencoder is broken in countless respects,
generating an mpeg-ps is quite safe:

$ mencoder -demuxer lavf -of mpeg -mpegopts format=dvd -oac copy -ovc 
copy -o output.mpg input.ts 

eventually dropping -demuxer lavf if it doesn't work (lavf's demuxer
isn't nearly as permissive as my native TS demuxer (the default one)
but it has an advantage: strictly correct timestamps on all frames)

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Re: [linux-dvb] dvb mpeg2?

[Tim Farrington]

Nico Sabbi wrote:
> On Thursday 24 July 2008 15:57:06 Nico Sabbi wrote:
>
>   
>> be aware that demuxing the TS in its elementary streams implicitly
>> drops all timestamps (that are recorded in the PES headers), thus
>> recombining the audio and video streams will produce a
>> desynchronized output, unless you are lucky.
>> There simply aren't enough informations to keep synchrony without
>> timestamps. With your method if a stream is corrupt
>> you will likely see a desynchronization from the first breakage
>> onward, while working on the TS the muxer has a chance to recover
>>
>>     
>
> BTW, although mencoder is broken in countless respects,
> generating an mpeg-ps is quite safe:
>
> $ mencoder -demuxer lavf -of mpeg -mpegopts format=dvd -oac copy -ovc 
> copy -o output.mpg input.ts 
>
> eventually dropping -demuxer lavf if it doesn't work (lavf's demuxer
> isn't nearly as permissive as my native TS demuxer (the default one)
> but it has an advantage: strictly correct timestamps on all frames)
>
> _______________________________________________
> linux-dvb mailing list
> linux-dvb@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
>
>   
Hi Nico,
Yes I wondered about corrupt streams, so I watched projectx in action 
carefully.
I need to understand it a bit more, but it found many corrupt timestamps
while demuxing, and repaired on the run. Time will tell, however I have 
some progress,
and I can't fault the process yet!

I intend to try all of everybody's suggestions. One question - with 
mencoder why format=dvd?

Regards,
Timf

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Re: [linux-dvb] dvb mpeg2?

[Nico Sabbi]

On Thursday 24 July 2008 16:13:22 Tim Farrington wrote:

> Hi Nico,
> Yes I wondered about corrupt streams, so I watched projectx in
> action carefully.
> I need to understand it a bit more, but it found many corrupt
> timestamps while demuxing, and repaired on the run. Time will tell,
> however I have some progress,
> and I can't fault the process yet!
>
> I intend to try all of everybody's suggestions. One question - with
> mencoder why format=dvd?
>
> Regards,
> Timf

because the default is mpeg2, with too many restrictions on the
 muxrate and because sooner or later you will want to burn to dvd.
The muxrate is a bit higher, but who cares? :)
Otherwise you can use -of mpeg -mpegopts format=mpeg2:muxrate=10800
or something like that

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Re: [linux-dvb] dvb mpeg2?

[Mark Fraser]

On Thursday 24 July 2008 13:02:17 Tim Farrington wrote:

> Hi Nico,
> I was a huge fan of avidemux until about 2 hours ago when I discovered
> that editing a file caused all sorts of grief with a/v sync.
> Its doc's tell me to send the file through Projectx first, etc
>
> Hence, I was attracted to gopchop.
>
> All I would like is an mpeg gui editor which can simply edit a file
> dumped from
> my dvb stream. I've tried many such as Cinerra (I think that's its name),
> but this help from Tobias may give me a clue as to why many of them
> won't open
> these files - they are MPEG2-TS and the apps perhaps need MPEG2-PS

I tend to use dvbcut for editing MPEG2-TS files these days unless it's a 
programme I recorded from five US then I have to run it through projectx and 
avidemux first otherwise I get a flickering effect when I play the file from 
DVD.


-- 
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| \/ | Somerset   /Using Kmail on Kubuntu Hardy Heron
|    |___________/You know what the sig means! 


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