I apologize if this is the wrong forum. I've been trying to find a program or if even one exists, that can encode mpeg-4 with lossless audio. My problem is, I am trying to put a vid on my gmini400 (which accepts mpeg-4 formats) and would really like lossless sound, I'm not too worried about vid as much as aud because it's a concert dvd. Usually I use AutoGK or PocketDivx with audio compression of 320kbs or 256kbs. When I try to use the option of direct audio stream (no compression), the files will not play on my gmini... I'm assuming because it does not support AC3 audio. So want I want to find or figure out if it even exists, is a mpeg-4 format that will allow lossless, or much higher sample rate than 320kbs... thanks for the help
Just so you'll know, AC3 is not uncompressed. That would be LPCM. All DVD players support AC3 and LPCM, so if yours won't play the audio, you're doing something wrong. Also, even Dolby 5.1 is encoded and compressed, so re-encoding this DVD, which almost certainly is using AC3 audio, to PCM would be pointless. Won't sound any better, but it will take up a lot more space.
Ok.. I know AC3 is compressed... but it's a lossless compression..I guess I miss wrote about the direct audio copy being uncompressed, it would be AC3 I assume, though I'm not sure what audio it puts it in when you select that option.. and I'm not playing it in a dvd player.. I'm playing on my gmini400 pmp... as far as 5.1, the dvd (as most do) has several audio tracks, one being stereo.. after searching though, I think I've found that the gmini400 will only play vids with mp3 and adpcm audio... which kind of stinks because it has the ability to play lossless pcm audio files, just that the video doesn't support it I think...unless it can play another form of mpeg-4 that has lossless audio... which I don't know if one exists.. I know there was talk of developing one a few years back
Hi guys, As I have noted elsewhere, AC3 is heavily compressed, but pretty nicely done. The compression standard is 'transparent' which means if bitrate is increased 9 out of 10 people cannot detect it; if the bitrate is reduced however, people begin to notice. I believe 5.1 is something like 448kbs, and 2.0 is 192kbs. This compares well with a 192kbs CBR MP3, but whether 192kbs VBR could provide better quality is a good question. Anyway, an MP3 at 320kbs ('insane' preset) is entirely transparent. I did Led Zeppelin - The Song Remains The Same like that (who cares about the video!) and sound was very good. Then I figured WTF and just used the DVD's AC3 2.0 audio, directly, for my backup (XviD MPEG4 AVI). MP3 is never gonna sound better, right? Don't care how many bits you throw at it... you could even make it larger than the AC3 I s'pose (which would be unfortunate.) Anyway, is your concert DVD audio 5.1 or 2.0? We can make you a nice MP3 ~180MB (2 hours) that will sound great. AC3 2.0 will be right around this filesize too, while AC3 5.1 is more like ~500MB. Of course, LPCM (or WAV) would be ~1.5GB, LoL If I backup to 1400MB AVI (2 CD-Rom) which is rarely, I will use 5.1 audio directly... you can see how it's not gonna fit with video into 700MB container very well, LoL ;^) The chief benefit of lossless audio is being able to re-constitute the original CD-quality song again (kind of like a better powdered coffee); this is the 'lossless' referred to, and does not necessarily describe the actual listening experience. Most lossless technologies perform about ~50% compression - amazing really, however this compares poorly in filesize to insane-preset MP3 which will be smaller. Insane-preset is actually more compatible MP3 than the VBR I usually make, because it's CBR :^) It plays back on anything that can handle the bitrate (some portables have limit I know.) But it is good, I recommend it. Anyway, I ramble, hope this helps, Regards
ok..thanks for the reply, so what I gather from your post then is that DVD's are originally encoded with AC3 which is LOSSY? I guess if that is the case, when I use the 2.0 (stereo) track, 320kbs should be just fine... that's crazy though.. I never knew the industry standard for dvd's used lossy compression for their audio tracks... I guess on alot of movies it doesn't matter... but I'm thinking something like Star Wars , or something with alot of sound effects and THX, you would be able to tell a difference.. maybe not.. here's just an curiousity question then... was audio on VHS ever compressed? The thing is.. I do remember that after I used pocketdivx to encode a .vob, when I selected direct audio copy, the resulting bitrate for the file was listed as something REALLY high... something like 1000kbs...
Well you wouldn't use those exact words, it's out of context. Lossy refers to loss of original signal information when the file is decompressed back into its native recorded format. These hollywood movies are recorded on huge multitrack digital rigs and mixed down to 6 channels in the DVD-standard AC3 format. Is there some loss? Well, yes I s'pose but for all intents and purposes the AC3 5.1 is 'source-quality' for we who are working with the audio. It's our starting point, and whatever you do to it you're not going to improve it, y'know? Again, don't think about 'lossy' in the context of the playback listening experience. L8R
Yeah.. I guess that makes sense... I just consider myself an audiophile and hate to see this trend where, mainly with music, everything is heading into so many avenues where lossy compression is accepted.. you can tell me that you can't hear a difference between lossless and mp3... but I know I can.. but since the DVD's are originally in AC3, I guess it doesn't really matter much.. and that's the price of being able to get the video and audio all onto one small 8gig dvd. I did a recheck btw and the audio file I was talking about was at 448kbs, I don't know where I got 1000kbs... but I also think it was the 2.0 stereo track.. so maybe both 5.1 and 2.0 are 448kbs... anyway, thanks for the help
Yes. Yes! Precisely exactly, it is a great peril. Back 'in the day' we bought direct-to-CD audiophile recordings (dunno if you're familiar with Chesky stuff) and years ago when PCM was new, those were good CDs. We were deeply suspicious of the whole CD PCM thing in the 80's but it seemed to us those special CDs might be even better than vinyl. These days, the bloody music's been all stepped-on, it's all cut y'know? And it's insidious, it's like polluted water but it looks the same... you can't tell... smells the same... but it's dead. People can't get into the concept of Quality - they ask: "Can I increase the bitrate of this crappy 96kbs joint-stereo MP3, I want to increase it to 256kbs. It should sound real good then, right?" They don't get it; people have been told or have heard that 'digital recording is an exact copy with no degradation of the signal' and when they burn a music CD from downloaded MP3s they know not what they do! Someone else has taken coffee and powdered it (hopefully they knew what they were doing) and sent it to you. You reconstitute it - you have hot powdered drink, and the discussion of the quality of the original coffee seems now far away... Stick strictly to store-bought compact disks, factory-pressed, hopefully by top-quality engineers and ideally by audiophiles, is all we can do I suppose. Education is the key though (what we do here). ddp says teach & learn, L8R
Concert DVD's will generally contain LPCM which is lossless. DVD specs also allow for DTS which generally uses a much higher bitrate than AC3. MPEG-4 specs do infact cover lossless audio. However we aren't talking MPEG-4 here. We are talking MPEG-4 video in an avi container which really has nothing to do with MPEG-4 specs. As far as mp3. Lame 3.97b2 with say -V2 --vbr-new is generally considered transparent. Pretty sure on a recent 128k listen test they used -V5 and most people found that to be transparent.
