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| TCmullet |
| Posted: May 26 2003, 07:03 PM |
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Hi Fcc. Okay, I've gotten my .mp2 stream into the divx .avi. I guess I don't mind that the divx player 2.1 won't play it. But once I have this divx avi with mp2 audio in it, I have to be able to run VirtualDub to convert the mp2 audio to something else later on. But Vdub won't decode the audio! How can we get around this? It's useless to get my mp2 file into the avi (which I strongly wish to do), if I can't ever decode it again to convert it to something else. Can you help?? I think an mp2 "acm" codec is needed, but I haven't been able to find anything. I would have thought that if mp3 is an advance to mp2, then it should be backward compatible. (Mp2 at 384k is better than mp3 at any bitrate.) |
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| fccHandler |
| Posted: May 26 2003, 11:06 PM |
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TC welcome to the forums! I'm glad you decided to go public. 
| QUOTE (TCmullet @ May 26 2003, 03:03 PM) | | once I have this divx avi with mp2 audio in it, I have to be able to run VirtualDub to convert the mp2 audio to something else later on. |
I don't understand that. If you know somehow that you are going to convert the audio later on, then you might as well convert it when you convert the MPEG. The whole idea of the "direct audio stream copy" feature is to preserve the audio so it doesn't get converted to something else.
| QUOTE | | It's useless to get my mp2 file into the avi (which I strongly wish to do), if I can't ever decode it again to convert it to something else. |
It's not difficult to decode it. Just use VirtualDub to save it out as a WAV (in direct stream copy mode), then use any MP3 decoder to decode the WAV. But surely you realize that every time you decode/encode you're losing quality, so I still don't understand why you would ever want to convert an AVI (which was already converted from an MPEG) a second time.
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May the FOURCC be with you... |
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| TCmullet |
| Posted: May 27 2003, 12:36 AM |
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Hey, fcc, glad to be here. Your questions are good, but very complicated to respond to quickly. And am very short of time the next few days. Will reply more later. But for now, I have urgent need to resolve what is possible.
I've been chagrined to spend hours searching the web and failing to find an .mp2 ACM codec, whereas there appear to be numerous mp3 codecs around. I want mp2 (for reasons to be discussed later), but everything in divx world appears to be mp3. Drat!! I want to play divx avis on DVD player in future, but if they won't play then I've gotta convert mp2 to mp3 later JUST to get future-dvd-player and divx player to play. But Vdub won't do it! And Divx player won't play mp2 now. Unless it's part of mpeg2 program stream.
Why can't the world make sense? Anything that records/plays mp3 should record & play mp2 the predecessor.
Well, I've already gone into part of my reasons... (hard not to vent a bit). Will discuss it more later when I'm not about to get fired from a paying job for not having enough of it done. (d_mn video hobby)
But the bottom line is: Can anyone help me put the .mp2 data into the AVI w/Divx 5 video, then easily playing it and be able to convert the audio to something else later?
I'm feeling pretty desperate.
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| fccHandler |
| Posted: May 27 2003, 02:17 AM |
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| QUOTE (TCmullet @ May 26 2003, 08:36 PM) | | But the bottom line is: Can anyone help me put the .mp2 data into the AVI w/Divx 5 video, then easily playing it and be able to convert the audio to something else later? |
The bottom line is, you can do all of that now.
VirtualDub-MPEG2-AC3 can put the .mp2 data into the AVI w/DivX, Media Player 6.4 can easily play it, and VirtualDub + BeSweet can convert it later to almost anything you want, as I explained before.
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May the FOURCC be with you... |
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| ChristianHJW |
| Posted: May 27 2003, 09:06 AM |
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| QUOTE (fccHandler @ May 27 2003, 04:17 AM) | | VirtualDub-MPEG2-AC3 can put the .mp2 data into the AVI w/DivX |
fcchandler,
you care dropping a note to Cyrius about this ? For matroska muxing we are normally trying to use native matroska codec IDs wherever possible, means 'A_MPEG/L3' for MP3, and 'A_MPEG/L2' for MP2 accordingly.
In the first release Cyrius was forced to use 'A_MS/ACM' as codec ID and copy the WAVEFORMATEX structure in KaxCodecPrivateData ( thats what we always do for our so called ACM compatibility mode ), as we noticed that when a MP3 was simply transmuxed from AVI we dont know the blockboundaries precisely, and this is mandatory to know for natively muxed matroska audio streams.
As an effect of that, Cyrius was using the native matroska MP3 codec ID only for
- VBR MP3
- external MP3 streams
and ACM compatibility mode for MP3 CBR from AVI.
As VdubMod is using your MPEG2 parser/decoder code by default, this means we can transmux MP2 audio from the DVD into MKV files now, and we have to make a decision if we use native codec ID ( only possible if we know where the frame boundaries are ) or MS/ACM mode.
I know one day i will be able to motivate you to add MPEG1/2 video transmuxing into matroska from VdubMod also  .....
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Visit the unofficial Virtualdub support forum on http://forums.virtualdub.org - help to reduce the big number of emails Avery Lee is getting every day !!
Support matroska as container and Gstreamer as the only truely open, x-platform multimedia platform .... |
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| fccHandler |
| Posted: May 27 2003, 05:23 PM |
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[RANT]
I still believe the MPEG container is the best container for MPEG content (video and audio), and I don't recommend putting MPEG content into anything else. The little kludge I added to allow a direct audio stream copy was mostly to satisfy those people who had asked me if it were possible to do. It's possible now, but that doesn't necessarily mean it's a good idea.
The designers of MPEG not only described the algorithms to compress/decompress the content, but they also specified the structure of the container itself. In a sense, putting MPEG video or audio content into any other container is a violation of the spec.
I think that VirtualDub's support of MPEG1 (and certainly my MPEG2 support) was primarily intended to allow you to process and reencode MPEG content to AVI, particularly TV captures. It wasn't intended for ripping DVDs or transmuxing raw MPEG. I suppose some VirtualDubMod developers might have these goals in mind, but it's hard to justify IMHO.
Here's the way I look at it: AVI, ASF, WAV, MOV, OGM, and Matroska are all flexible container formats that can hold different kinds of content. The MPEG container was designed specifically for MPEG, it's not flexible, and it can only hold MPEG. It's pointless to take the content out of its natural habitat unless you're going to recompress it.
[/RANT]
Cheers!
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May the FOURCC be with you... |
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| ChristianHJW |
| Posted: May 28 2003, 02:03 AM |
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fcchandler, here are the reasons why putting MPEG audio/video streams into a different container can make sense :
1. MPEG sucks for editing, and this is right for MP4 also. We are talking to the MPEG4IP people right now to find out what it takes to acccept matroska as input format for mp4 creator, while MP4 can be used as input format for MOsu's mkvmerger pretty soon.
In short, we will have tools to transmux MP4 into MKV, edit the files on VirtualdubMod, and then remux them to MP4 after haevy editing. This way MKV is used a temporary editing container for MP4. The very same could be done with normal MPEG streams, making editing of a captured material ( cutting out ads, etc. ) a breeze before feeding them into VdubMod for final transcoding into an MPEG4 AVI/MKV/OGM or whatever ... this is possible because the MKV container is editable by design without using the codecs ....
2. MPEG container doesnt have a proper spec for text subtitles, only the SVCD standard will allow subs, and only bitmap image subs. I can see use where people want to keep the original MPEG audio and video content unaltered, but want to add several subtitles streams to the file without having a huge overhead, MKV was ideal for that. If you ever wnat to make a valid MPEG from it, transmux the MKV into MPEG leaving away the subs, or even converting them to SVCD compliant image subs.
3. Same as above, but with audio. Why shouldnt people want to add several other audio tracks ( Vorbis, AAC, etc. ) to existing MPEG content for storage purposes, but without altering the MPEG streams themselves, so they always can make hardware compliant stuff from it again later ?
4. MPEG has also limited tagging support, and no file attachements are possible. BBB from the Gstreamer development team is currently adding MKV support to Gstreamer because at his workplace, a NL based broadcaster, they are considering MKV as general use storage format, to allow a common tagging system for all the different compression formats they have  .... this would be the first known commercial application of matroska BTW  !!
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Visit the unofficial Virtualdub support forum on http://forums.virtualdub.org - help to reduce the big number of emails Avery Lee is getting every day !!
Support matroska as container and Gstreamer as the only truely open, x-platform multimedia platform .... |
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| fccHandler |
| Posted: May 28 2003, 06:24 AM |
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| QUOTE (ChristianHJW @ May 27 2003, 10:03 PM) | | the first known commercial application of matroska |
I must say, that's pretty impressive. Good job!
You make many valid points, and I could continue my rant but I don't want to get into an argument. I wish you the very best of luck and I hope you find glory with Matroska.
I'm still sticking with MPEG2.
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May the FOURCC be with you... |
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| ChristianHJW |
| Posted: May 28 2003, 12:46 PM |
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| QUOTE (fccHandler @ May 28 2003, 08:24 AM) | | You make many valid points, and I could continue my rant but I don't want to get into an argument. |
fcchandler,
i loved to have an argument with you about this, because your technical expertise with respect to MPEG is certainly unrivalled in the whole matroska team and even our complete environment, so your input here was incredible precious to us.
You know, we have a couple of good programmers in the team who loved to contribute more, but cant do anything sensible because they dont have the necessary background information to do so. Some hints from you how to do that, or what problems we have to face/circumvent, taking maybe 30 mins of your admittedly precious time, maybe cant be weighed in gold for us  !!
spyder already started making an CLI based app ( thats fine for a start ) called MPV2MKV, and the plan was it should be able to accept any MPEG elementary stream on its input. He stopped working on it when he started to read about GOPs, and that those may change on every keyframe !! matroska has the flexibility to introduce a new element to handle GOPs, and even without breaking anything in current specs, thanks to EBML. But we really could use some advice how to handle the stuff correctly.
If you ever find a minute to think of possible ways of doing it, and let us know, you will be our shining star !
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Visit the unofficial Virtualdub support forum on http://forums.virtualdub.org - help to reduce the big number of emails Avery Lee is getting every day !!
Support matroska as container and Gstreamer as the only truely open, x-platform multimedia platform .... |
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| TCmullet |
| Posted: May 28 2003, 04:22 PM |
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Dear fcc, hjw,
i'm very much interested in your discussion. keep it up. hope i can get into the fray as well. after i do some more tests, i wish to give you both some user feedback as it relates to this issue of containers, mpeg, avi, etc. This is very important to me, so i hope we can all interact. excuse the non-caps..just badly sprained left pinky in volleyball last night. always took left pinky on the left shift key for granted. not anymore. the a key hurts too, but can subst 4th finger for that. |
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| fccHandler |
| Posted: May 28 2003, 05:47 PM |
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@ChristianHJW:
Everything I know about MPEG I learned from reading specs and studying other people's source code. If background info is what your VirtualDubMod developers need, there is an incredible wealth of MPEG1/2/4 technical info here.
I'm sorry I can't get as excited as you about VirtualDubMod and Matroska, honestly I've never found any use for either of them. But that's just me. If I want to watch one of my DVDs, I plop it in the tray. I've studied the DVD structure but I've never bothered to try to rip one. I don't believe in laser rot. I don't encode movies for other people. I have no need of multiple language tracks. I think Vorbis audio is horrible. I hate subtitles.
I love VirtualDub just the way it is. I've even gone to some silly extremes to keep my MPEG-2 changes from interfering with the rest of the program. I could probably have derailed some of the code in Audio.cpp to make it possible for VirtualDub to decode and preview MPEG Layer I/II and AC3 in AVI files. Maybe I'll do that someday, but it feels wrong somehow.
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May the FOURCC be with you... |
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| fccHandler |
| Posted: May 29 2003, 08:06 PM |
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Uploaded VirtualDub-MPEG2-AC3 1.5.4 today.
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May the FOURCC be with you... |
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| Sajal |
| Posted: May 30 2003, 12:41 AM |
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That was a real quick release, I was opening this thread to post a request and whoa! I needn't even request, don't you even have a Life?
Thanks a Lot,
I mean It, this time
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'Veni, Vidi, Velcro' - I came, I saw, I stuck around |
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| fccHandler |
| Posted: May 30 2003, 01:45 AM |
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| QUOTE (Sajal @ May 29 2003, 08:41 PM) | | don't you even have a Life? |
Of course not, I'm a programmer! 
Actually I'm on vacation right now but I just realized I've spent 99% of my vacation in front of the computer...
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May the FOURCC be with you... |
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| TCmullet |
| Posted: May 30 2003, 01:47 AM |
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blame it on phaeron... he keeps making improvements to the baseline. fcc is only prompt in keeping up. great work phaer & fcc. |
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