Multiplexing and demultiplexing MPEG1 and MPEG2

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Multiplexing and demultiplexing MPEG1 and MPEG2

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HamaZ

Junior Member

8. May 2006 @ 13:01

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This is the task I must do:

I have an MPEG2 material (recorded by a Digital Video Broadcast card). The sound is compressed in MPEG1 L2 format, 48KHz sampling rate.

I need to demultiplex that sound from that file and multiplex it into another MPEG1 file which currently has no sound in it.

How to achieve this? Whih application to use? The sound must NOT be recompressed.
Will the 48KHz sampling rate be a problem for the MPEG1 file (will it conform to the MPEG1 standards)?

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SOCOMII

Senior Member

18. May 2006 @ 16:38

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Use VirtualDUB-MOD to demux STREAMS > STREAM LIST > then select the sream and hit "Demux"
http://prdownloads.sourceforge.net/virtualdubmod/VirtualDubMod_1_...

Then get TempgEnc and go to FILE > MPEG TOOLS > and the pick the multiplexing method that best suits your needs.

This should acomplish what you are trying to do.
-Also You sould not lose any quality because you are not re-encoding just demuxing and remuxing

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This message has been edited since posting. Last time this message was edited on 18. May 2006 @ 16:39

HamaZ

Junior Member

19. May 2006 @ 00:57

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Thank you for the reply.

I will try what you said. The only question remains does 48KHz sampling rate conform to the MPEG1 specifications? In other words, will an MPEG1 file with 48KHz audio be playable on stand-alone players and software/hardware MPEG players (like PowerDVD or some MPEG decoders)?

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aldaco12

AfterDawn Addict

19. May 2006 @ 01:42

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No, (S)VCD are sampled 44.1 kHz.
The best thing to do is using VirtualDub (not -Mod), set audio____Full processing mode and File__Save WAV (maybe, in VirtualDubMod even [Save WAV] works, but I notice that sometimes the sound is simply demuxed and not uncompressed. VirtualDub is safer. Also, you must take care to obtain a file which is 10.1 MB x length (in minutes) large.
After that, use HeadAC3he (one of the simplest applications); load the WAV as 'source file', select 'MP2' (MPEG Layer 2) as 'destination format' and check the box 'resample to [44.1 kHz]'.
After this transformation (once I did MP2 48 kHz -> MP2 44.1 kHz and HeadAC3he lowered the audio volume, maybe due to a HeadAC3he bug, and therefore I suggested you to extract the sound as uncompressed WAV). Your MP2 will be fully (S)VCD compliant (224 kbps 44.1 kHz) and you'll be able to multiplex it.

Another application you could use is FFMPEG GUI, but is less 'automatic' in its options. You'll have to choose manually: Format='MP2'; Bitrate = '224' (kbps); 'Sampling rate' = 44100 (Hz).

Remember: (S)VCD standard is 224 kbps (but, maybe, your DVD player accept also a MP2 with less bitrate, even 128 kbps. But why should you want to lower the audio's bitrate, since the video's is constant (1150 kbps)?

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This message has been edited since posting. Last time this message was edited on 19. May 2006 @ 01:48

HamaZ

Junior Member

20. May 2006 @ 09:05

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Thank you for this answer. I am not a beginner in audio/video domain, but I am also not an expert. I consider myself to be on some intermediate level of knowledge about it.

I supposed that for (S)VCD I would probably have to use 44.1KHz audio.

But if I only want to make standard multiplexed MPEG1 clips (.MPG), which will be distributed on data CDs, flash memories, etc. and played in standard Windows Media players, do I have to resample to 44.1KHz for them too? Or can I just multiplex into them these 48KHz audio streams I already have?

In other words, is 48KHz audio valid for such "ordinary" MPEG1 clips?

Maybe the only problem would be if the sound card is older so it can not play 48KHz audio?

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afterdawn.com > forums > archived forums > mpeg-1 and mpeg-2 encoding (avi to dvd) > multiplexing and demultiplexing mpeg1 and mpeg2


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