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View Full Version : Re-encode AC3 to LPCM using TMPGenc


vladsmythe
2008-05-17, 04:09 PM
I am currently seeding this at another site:

Dennis McNally
KQED Studios (PBS)
San Francisco, CA
8-5-95
Another video from the Graceful Duck Archive.

Cable > SuperBeta HiFi > Playback Sony EDV-9500 >
Standalone Panasonic DMR-E50 (XP)
No Artwork
Chapters: Approximately every 5 minutes
NTSC
Stereo
TRT: 24:12
Audio codec: AC3
Audio bitrate: 256 kb/s
Video codec: MPEG2
Video bitrate: 9164 kb/s
Picture resolution: 704x480

Recorded just four days before Jerry Garcia's passing,
Grateful Dead publicist and official historian Dennis McNally
joined Greg Sherwood during the KQED pledge drive. The
segments presented here were during pledge breaks in the
broadcast of "Dead Ahead". Always informative, Dennis
answers the cursory questions that non-Deadheads always
seem to ask, but also sheds light on other topics. It is
bittersweet to here him talk about the Dead's future -
upcoming shows and sessions for the next album. There
are also a couple of pre-recorded Bob Weir messages for
PBS as well a short piece "Bob Weir on Saint of Circumstance".
I recorded this as it happened, the edits were done on my
betamax decks. I hope you enjoy.

I know that AC3 audio is a huge no-no here, but if I re-encode it with TMPGenc to make it LPCM will that satisfy the mod(s)? I think there are many members here who would enjoy this video.
http://i180.photobucket.com/albums/x316/vladsmythe/snapshot20080517111924.jpg
http://i180.photobucket.com/albums/x316/vladsmythe/snapshot20080517111445.jpg

Thulani
2008-05-17, 04:12 PM
If the video bitrate writen by you is right, you'll make a non-compliant DVD converting AC3 to LPCM.

vladsmythe
2008-05-17, 04:16 PM
Well then, I'll leave it as a "Crappy compressed standalone video" like all my others.
Just thought I'd ask. Thanks for the heads-up!

U2Lynne
2008-05-17, 04:53 PM
Well then, I'll leave it as a "Crappy compressed standalone video" like all my others.
Just thought I'd ask. Thanks for the heads-up!
Personally, Bill, I really don't care. Yes, there are people who care that it is AC3 and not LPCM, but that is why we require this info to be spelled out in the torrent notes. If people don't want DVDs with AC3 audio, then they should just skip over the torrent. This is really something you just can't do anything about at the moment.

vladsmythe
2008-05-17, 04:55 PM
Maybe I should buy better equipment! I'll look into it.:)

LeifH12345
2008-05-17, 05:24 PM
Wait, so the reason you're asking this is because you don't have equipment to do LPCM audio?

If not, just re-transfer the tape

vladsmythe
2008-05-17, 05:43 PM
Wait, so the reason you're asking this is because you don't have equipment to do LPCM audio?

If not, just re-transfer the tape

Exactly. I use a Standalone Panasonic DMR-E50 recorder. It records with
AC3.

I wish schmoe75 was around to help. He's the best at this stuff!:lol4::lol4::lol4:

LeifH12345
2008-05-17, 07:01 PM
Well I can tell you myself, the only way it's going to work (properly) with LPCM is if you get different equipment. Surely a connection directly to your computer rather than a standalone would be cheaper and better. You've got the playback equipment.

good luck

vladsmythe
2008-05-17, 07:12 PM
Logistically that is a nightmare. I don't need more equipment in my bedroom. Also, I watch what I transfer while I party with friends, so it's a social thing too. I'm cool with AC3. It's not as if it's audio tape. It's all compressed TV via cable anyway. If anyone wants to upgrade the audio portion of any of my vids they can knock themselves out. I think most of my torrents are kind of obscure though.
Thanks for the help. If anyone knows of a standalone that does LPCM let me know. I'll buy it, and sacrifice the video quality and do them at a lower bitrate.

tgunn2760
2008-05-17, 07:45 PM
Logistically that is a nightmare. I don't need more equipment in my bedroom. Also, I watch what I transfer while I party with friends, so it's a social thing too. I'm cool with AC3. It's not as if it's audio tape. It's all compressed TV via cable anyway. If anyone wants to upgrade the audio portion of any of my vids they can knock themselves out. I think most of my torrents are kind of obscure though.
Thanks for the help. If anyone knows of a standalone that does LPCM let me know. I'll buy it, and sacrifice the video quality and do them at a lower bitrate.

You can't "convert" AC3 to LPCM, what you can do is decompress it to wav, then, if the original audio is low you can boost it in Gold Wave-double it in fact.

It won't be LPCM, it will be bloated AC3. But it will sound better, especially if you boost the volume.

As for SA recorders that record in LPCM, I have a Pioneer DVDR-450 Hs, the models probably have changed now but you can read the specs online and find one that will record in lossless audio.

Some makes will only record one hour in LPCM, not this. I have recorded two hour programs, edited out the commercials, and was left with a 90 minute file which I then split into two.

One hour of video with LPCM is the size of a DVD5, so it fits nicely. You can also add chapters to the recording, split it and then copy to DVD-RW with the "one touch copy" option. That will preserve the chapter points. If you use the other record to disc option, it will add random 10 minute chapters.

The video bitrate the recorder uses for LPCM recording is 8000 kbps.

LeifH12345
2008-05-17, 09:17 PM
It won't be LPCM, it will be bloated AC3.

Why the fuck would you do that? :wtf:

He's looking to upgrade the audio, not make it worse :stfu:

Thulani
2008-05-18, 03:44 AM
Logistically that is a nightmare. I don't need more equipment in my bedroom. Also, I watch what I transfer while I party with friends, so it's a social thing too. I'm cool with AC3. It's not as if it's audio tape. It's all compressed TV via cable anyway. If anyone wants to upgrade the audio portion of any of my vids they can knock themselves out. I think most of my torrents are kind of obscure though.
Thanks for the help. If anyone knows of a standalone that does LPCM let me know. I'll buy it, and sacrifice the video quality and do them at a lower bitrate.
I don't have experience with tape transfers, but I think you can preserve video quality & record to LPCM. You just need to do 2 transfers of the same tape. 1st transfer you'll do it with high video quality (8000kbps) & loosy sound, & 2nd transfer you'll do it with low video quality & lossless sound. Then you demux the shows & remux with the better part from the two transfers.
If I'm wrong with something, I'm sorry.

KoolKat
2008-05-19, 05:41 AM
It won't be LPCM, it will be bloated AC3.

He's looking to upgrade the audio, not make it worse :stfu:

As you called him a noob , i would like you to explain how it would be worse.

But before you do i will add>
AC3 to PCM is uncompressing.It will be the same my friend..NOT worse ,just a bigger AC3.Dolby on Linear

I will also add for Vlads benefit that if you recorded them onto VHS via a TV broadcast ,then the likely hood that they were mp2 at 192kbps is very high.Some "specials" would of been in AC3.
Rare for a PCM stream broadcast from yesteryear.

I tell you this so that if you do just bloat your audio to PCM,you at least will know 1 thing for sure and that is that whatever it was to start with ,it's still lossless from your master recording.

That...will not make it worse and could indeed upgrade it because if some audio was recorded as mp2 ,then the re-transfer to AC3 would be lossy from source recording.

K_K

PS: You might want to edit your noob smiley out now.....nOOb

MeFirst
2008-05-19, 06:43 AM
Honestly, what's the point of all this since judging from the description of this particular video it's just people talking. Who cares what the sound quality is like anyway unless there's music involved.

To point out a few things though, there are not many standalones that record audio in LPCM, most will use AC3 so that higher video bitrates can be used. Although it is possible to use video bitrates over 8000kbs with LPCM resulting in a "non-standard" DVD, most DVD players these days won't have any trouble playing them anyway.

Also, many people assume because AC3 is a form of compression they immediately equate it to the horrible MP3 compression, which is totally different. AC3 is hardly a "crappy compressed" format, it's used on virtually every commercial DVD released (yes, AC3 is Dolby Digital). Due to the bandwidth limits of a DVD, Dolby Digital is preferred so that the higher video bitrates can be used for smoother video.

And as Kool Kat pointed out, most cable and satellite broadcasts use audio compression to begin with, so you're not getting true lossless audio right from the start. Your VCR (or Beta in this case) recorded it in LPCM of course, which is basically the same thing as plugging in your portable MP3 player to your PC and using a software audio recorder to record the music off it to WAV in real time (not that broadcasts use MP3 audio, it's just an example). So right from the beginning, the damage has already been done. Of course, recording from the VCR to LPCM keeps the audio the way it is without further compression which would be best, but when it comes right down to it, AC3 is really not a bad compression format. If it were, it wouldn't have been used by pretty much every single movie studio for the past 16 years or so.

vladsmythe
2008-05-19, 09:35 AM
Thanks for the infoMeFirst. I feel better about my efforts here after reading your message. Based on that, I have decided that I will ignore the nay-sayers and continue to share my videos here. Damn the torpedos, full speed ahead!
vladsmythe - The Graceful Duck Archive...."More than a collection, a way of life."

tgunn2760
2008-05-19, 10:30 AM
Honestly, what's the point of all this since judging from the description of this particular video it's just people talking. Who cares what the sound quality is like anyway unless there's music involved.

To point out a few things though, there are not many standalones that record audio in LPCM, most will use AC3 so that higher video bitrates can be used. Although it is possible to use video bitrates over 8000kbs with LPCM resulting in a "non-standard" DVD, most DVD players these days won't have any trouble playing them anyway.

Also, many people assume because AC3 is a form of compression they immediately equate it to the horrible MP3 compression, which is totally different. AC3 is hardly a "crappy compressed" format, it's used on virtually every commercial DVD released (yes, AC3 is Dolby Digital). Due to the bandwidth limits of a DVD, Dolby Digital is preferred so that the higher video bitrates can be used for smoother video.

And as Kool Kat pointed out, most cable and satellite broadcasts use audio compression to begin with, so you're not getting true lossless audio right from the start. Your VCR (or Beta in this case) recorded it in LPCM of course, which is basically the same thing as plugging in your portable MP3 player to your PC and using a software audio recorder to record the music off it to WAV in real time (not that broadcasts use MP3 audio, it's just an example). So right from the beginning, the damage has already been done. Of course, recording from the VCR to LPCM keeps the audio the way it is without further compression which would be best, but when it comes right down to it, AC3 is really not a bad compression format. If it were, it wouldn't have been used by pretty much every single movie studio for the past 16 years or so.

If the audio is compressed during the broadcast, then you would be compressing it a second time if you used anything BUT LPCM during the transfer from VHS to DVD. MPEG2 to AC3 or AC3 to AC3 would be a second compression, especially if the bitrate is different.

8000 kbps video compression and LPCM audio is not bad for one hour of music. I have seen excellent video at lower bitrates. Most programs at about one hour, some are two hours, minus the commercials it's 90 minutes, those can fit on two DVD5s. A one hour program with lossless audio is about 4 GBs.

So, if Vlad can get a SA DVD recorder that will record audio at LPCM he would be better off. I am sure he can hook up his VHS to it and dub, and also record new programs in lossless audio.

saltman
2008-05-19, 10:53 AM
I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.

vladsmythe
2008-05-19, 10:56 AM
I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.
Such a shame. I have so much more to share.:(

tgunn2760
2008-05-19, 11:00 AM
I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.

AC3 is great for movies, LPCM is far superior for music.

Nowdays you see more and more DTS audio for commercially released music DVDs.

saltman
2008-05-19, 11:19 AM
Such a shame. I have so much more to share.:(I do not mean my statement to be directed at you personally. You SA transfers are less than ideal but it sounds like they are the best source available at the moment and are acceptable according to our present standards. The only thing that would be better would be if they were PC transferred, IMO.

vladsmythe
2008-05-19, 11:30 AM
Thanks for the positve and informative response saltman. I will have to buy another PC to do it, as my wife would kill me if I suggested doing it in my bedroom or the recroom/office. She likes things uncluttered. So when I buy a new box I'll give it a whirl in the Graceful Duck Archive storage vault (my garage). Until then, trust me to provide the best possible content in the best possible manner for now. Thanks again for the help.

scratchie
2008-05-19, 12:23 PM
She likes things uncluttered. Women!