Doom9's Forum - View Single Post - UPDATED: Compressing Audio before Shrinking a DVD (LPCM/ac3 5.1ch -> mp2/ac3 2ch)

Malcolm · 4th November 2004, 11:23

This guide describes how to compress DVD audio tracks. This is useful if you want to save space for the video part when shrinking from DVD-9 to DVD-5.

You need the following tools:
- a DVD Ripper (e.g. DVD Decrypter)
- PgcDemux
- an audio encoder (e.g. BeSweetGUI or BeLight)
- MuxMan
- VobBlanker

There are a few other guides out there. But these methods are fairly complicated, work only for DVDs with exactly one audio-track and also can't keep subtitles, chapters and menues.

This guide works for multiple audio tracks, preserves subtitles, chapters and the menue structure. It's also fairly easy. (with a certain basic-complexity)

and it should work for most DVDs.

According to jsoto, VobBlanker cannot process multiangle DVDs! I can not say if my method works in other exotic cases. (e.g. multiple PGCs per TitleSet)

Here's the guide (in case you want to compress the audio tracks of the main movie from a DVD):
1. Rip the DVD to your harddisk.
2. Open PgcDemux, choose the .ifo file for the main movie on the DVD. Demux all audio, video + substreams. Also create the Celltimes.txt + the logfile.
3. Use BeSweetGUI or BeLight to convert the demuxed audio tracks to any format you like (2ch AC3 or MP2) (*1).
4. Open MuxMan. Select the demuxed video track from step 2. Select all audio tracks you have created with BeSweet (take care for the right order: 0x80, 0x81,..) (*2). Select all demuxed substreams. Select the Celltimes.txt that PgcDemux has created. Create the VOBs + IFOs.
5. Open VobBlanker. Open the original, ripped DVD (NOT the one you have just created with MuxMan)! Select the main movie TitleSet + PGC (the one you have demuxed with PgcDemux). Select 'Replace' and choose the first VOB you have created with Muxman. Hit 'PROCESS!!' VobBlanker will correct the Coding Mode for all audio tracks that you have converted to their new format (Dolby AC3, MPEG-1).

That's it!
Now you have a DVD on your harddisk with compressed audio tracks. And you can transcode it with DVD-Shrink or any other program you like.

(*1) IMHO 160 kbit is a good choice for MP2 and 2ch AC3 compression. In PAL-land you can use MP2 if you want. In NTSC-land, AC3 is mandatory for DVDs (MP2 is optional). I recommend MP2 since BeSweet is not good in creating AC3 (bad sound quality). MP2 and AC3 should have a comparable sound quality at a bitrate of 160 kbit. Edit: If you really want to save space, you can go down to 64 kbit AC3s when encoding in mono(!). HeadAC3e produces much better AC3 than BeSweet. The quality of 64 kbit mono AC3s from HeadAC3e is also much better than 64 kbit mono MP2s.

(*2) It might be that you have to enter a delay for the audio tracks in MuxMan. According to jsoto the delays in the logfile of PgcDemux have the right values and can directly be entered in MuxMan.

The whole method is pretty mechanical and could easily be automated. PgcDemux has commandline-support. BeSweet too. If MuxMan + VobBlanker would also have commandline-support, then you could do everything with a batch-script or a few clicks (if you had a GUI-tool for this).
What i would REALLY like to see is the integration of PgcDemux into VobBlanker. Both tools are from jsoto. VobBlanker could then call BeSweet + MuxMan! And you would save a lot of manual interaction, selecting things, clicking around, copying VOBs, ...

I would like to thank especially jsoto for his tools VobBlanker + PgcDemux! Without them this all wouldn't be possible!

Feedback is welcome!

Greetings,
Malcolm

4th November 2004, 11:23	#1 \| Link
Malcolm Registered User Join Date: Sep 2002 Location: Germany Posts: 352	UPDATED: Compressing Audio before Shrinking a DVD (LPCM/ac3 5.1ch -> mp2/ac3 2ch) This guide describes how to compress DVD audio tracks. This is useful if you want to save space for the video part when shrinking from DVD-9 to DVD-5. You need the following tools: - a DVD Ripper (e.g. DVD Decrypter) - PgcDemux - an audio encoder (e.g. BeSweetGUI or BeLight) - MuxMan - VobBlanker There are a few other guides out there. But these methods are fairly complicated, work only for DVDs with exactly one audio-track and also can't keep subtitles, chapters and menues. This guide works for multiple audio tracks, preserves subtitles, chapters and the menue structure. It's also fairly easy. (with a certain basic-complexity) and it should work for most DVDs. According to jsoto, VobBlanker cannot process multiangle DVDs! I can not say if my method works in other exotic cases. (e.g. multiple PGCs per TitleSet) Here's the guide (in case you want to compress the audio tracks of the main movie from a DVD): 1. Rip the DVD to your harddisk. 2. Open PgcDemux, choose the .ifo file for the main movie on the DVD. Demux all audio, video + substreams. Also create the Celltimes.txt + the logfile. 3. Use BeSweetGUI or BeLight to convert the demuxed audio tracks to any format you like (2ch AC3 or MP2) (1). 4. Open MuxMan. Select the demuxed video track from step 2. Select all audio tracks you have created with BeSweet (take care for the right order: 0x80, 0x81,..) (2). Select all demuxed substreams. Select the Celltimes.txt that PgcDemux has created. Create the VOBs + IFOs. 5. Open VobBlanker. Open the original, ripped DVD (NOT the one you have just created with MuxMan)! Select the main movie TitleSet + PGC (the one you have demuxed with PgcDemux). Select 'Replace' and choose the first VOB you have created with Muxman. Hit 'PROCESS!!' VobBlanker will correct the Coding Mode for all audio tracks that you have converted to their new format (Dolby AC3, MPEG-1). That's it! Now you have a DVD on your harddisk with compressed audio tracks. And you can transcode it with DVD-Shrink or any other program you like. (1) IMHO 160 kbit is a good choice for MP2 and 2ch AC3 compression. In PAL-land you can use MP2 if you want. In NTSC-land, AC3 is mandatory for DVDs (MP2 is optional). I recommend MP2 since BeSweet is not good in creating AC3 (bad sound quality). MP2 and AC3 should have a comparable sound quality at a bitrate of 160 kbit. Edit: If you really want to save space, you can go down to 64 kbit AC3s when encoding in mono(!). HeadAC3e produces much better AC3 than BeSweet. The quality of 64 kbit mono AC3s from HeadAC3e is also much better than 64 kbit mono MP2s. (2) It might be that you have to enter a delay for the audio tracks in MuxMan. According to jsoto the delays in the logfile of PgcDemux have the right values and can directly be entered in MuxMan. The whole method is pretty mechanical and could easily be automated. PgcDemux has commandline-support. BeSweet too. If MuxMan + VobBlanker would also have commandline-support, then you could do everything with a batch-script or a few clicks (if you had a GUI-tool for this). What i would REALLY like to see is the integration of PgcDemux into VobBlanker. Both tools are from jsoto. VobBlanker could then call BeSweet + MuxMan! And you would save a lot of manual interaction, selecting things, clicking around, copying VOBs, ... I would like to thank especially jsoto for his tools VobBlanker + PgcDemux! Without them this all wouldn't be possible! Feedback is welcome! Greetings, Malcolm Last edited by Malcolm; 11th April 2005 at 09:28.