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| S_O |
| Posted: Apr 7 2003, 05:44 PM |
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Vdubmod Alpha Testing Team
Group: Vdubmod Alpha Testing Team
Posts: 102
Member No.: 57
Joined: 25-July 02
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Several companies have already MPEG-4 applications that not not just use MPEG-4 codec, they uses mp4-files, for example Quicktime, Envinio, Nero...
It seems to be on of the future file formats at least for big companies and it will get used more and more.
I´ve read that the file-format is not patented, so will VirtualDub be able to read MP4 in future?
For decoding the video VirtualDub could use ffmpeg, which uses patented technologie and therefore could cause legal problems. So VirtualDub could also simply use an existing VfW-codec like DivX, XviD, 3ivX, Dicas or ffvfw and output the video stream simply to them as if the mp4 would be an avi file (user should be allowed to set the fourcc).
For audio there is FAAD2, which is a perfect decoder, but also uses patented technologie. But also every MPEG-Audio Layer I / II / III decoder also uses patented technologie and normaly you would have to pay 75 US-Cent per unit ( http://www.mp3licensing.com/royalty/index.html ). On audiocoding.com (the official faad site) you can also download a compiled mp4/aac-winamp-plug-in, so there doesn´t seem to be big legal problems for decoders.
Will there ever be mp4-support in VirtualDub? If not, will there be in VirtualDubMod? |
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| ChristianHJW |
| Posted: Apr 8 2003, 01:29 PM |
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Advanced Member
Group: Moderators
Posts: 1768
Member No.: 2
Joined: 7-July 02
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You mean for decoding MP4 and compress them again using other codecs, so they fit into AVI finally ? I fail to see the sense in doing that ?
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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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| S_O |
| Posted: Apr 9 2003, 01:05 AM |
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Vdubmod Alpha Testing Team
Group: Vdubmod Alpha Testing Team
Posts: 102
Member No.: 57
Joined: 25-July 02
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| QUOTE | | You mean for decoding MP4 and compress them again using other codecs, so they fit into AVI finally ? I fail to see the sense in doing that ? |
No, just support for mp4, like for mpg. You want to open mp4, because you want to cut it, filter it or you are forced to another codec. Same for mpg-1. VirtualDub is a transcoding/transmuxing tool with many features like filtering etc. It should support all common formats/containers.
A picture editor, like PhotoPaint or PicturePublisher, you don´t watch you´re pictures in it, like you doesn´t use VirtualDub for watching videos, but you can open and save in very many formats, it´s not limited to bmp and tif. Because you want to change something in the picture, maybe sharpen, insert a text, resize.... Not only with bmp/tif-pictures. Same goes for videos, you want to change them (any kind of filter etc.) and VirtualDub is the best application for doing that. You´re videos are not always avi.
Of course this feature isn´t needed for DVD-ripping, but VirtualDub is much more than a dvd-ripping tool. |
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| ChristianHJW |
| Posted: Apr 9 2003, 10:15 AM |
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Advanced Member
Group: Moderators
Posts: 1768
Member No.: 2
Joined: 7-July 02
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Yes, but in any case, like with MPEG, you can only output to AVI after importing a MP4, so again, whats the sense in that ?
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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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| S_O |
| Posted: Apr 9 2003, 01:01 PM |
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Vdubmod Alpha Testing Team
Group: Vdubmod Alpha Testing Team
Posts: 102
Member No.: 57
Joined: 25-July 02
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[QUOTE]Yes, but in any case, like with MPEG, you can only output to AVI after importing a MP4, so again, whats the sense in that ? [QUOTE]After cutting/filtering etc. the video and recompressing it you can mux it back to mp4 (or any other format like matroska) with mp4creator for example. AVI is not a format like RM, once you have it you cannot do anything else than playing it, you can remux to another format. So VirtualDub doesn´t output the final file, it is just for processing the video. |
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| ChristianHJW |
| Posted: Apr 9 2003, 01:09 PM |
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Advanced Member
Group: Moderators
Posts: 1768
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Joined: 7-July 02
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Ok, i am slowly getting the point now. You consider to use Virtualdub to
- open/import a MP4 file, without audio ( AAC, VQF, AC3, whatever ) but just the video
- process/filter/reencode using a MP4 codec
- output as AVI
- mux AVI video with the original audio stream into MP4 again
Correct ?
Well, the only real problem i can see here is that most modern MPEG4 video codecs can use b-frames, and AVI cant really deal with it other than inserting dummy frames ( packed bitstream ). In the MP4 file the b-frames are in strict coding order, so the import filter had to respect that and reorder them, such that they could be processed with a MPEG4 VfW codec. After that, when reading the AVI file, the MP4 muxer had to reorder a 2nd time. Not impossible, but doable. Maybe matroska could be used as interims container instaed of AVI ..... then in a last step the final MP4 could be muxed from the interims matroska file ....
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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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| S_O |
| Posted: Apr 9 2003, 03:10 PM |
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Vdubmod Alpha Testing Team
Group: Vdubmod Alpha Testing Team
Posts: 102
Member No.: 57
Joined: 25-July 02
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If there are no licensing issues (there aren´t seem to be any with NekoAmp) it could also allow processing audio using FAAD2 decoder or what ever (if Layer I / II / II is used NekoAmp could be used for decoding). If AC3 (is that possible?) is used at least the MPEG-2 version of fccHandler could decode it with liba52.
Of course Direct Stream Copy should also be possible for audio (that is really needed eith MPEG-1/2! Direct Stream Copy for audio!).
At least VirtualDubMod should support that, because it can write Matroska files, so: No problem with B-Frames, VBR-audio etc.
That would also allow easy remuxing from MP4 to matroska.
But sometimes you just want to reencode a file, maybe to send it per email to somebody, you resize the video down to 320x240 and resample the audio down to 16kHz mono, to get a 2MB file instead of a 12MB. |
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