burning

[edward]

Can anyone help ? I can watch movies on my p/c with VideoLAN no problems at all but I cannot burn to disc, I have Nero and roxio + dvd r/w[/b]

[fkuehne]

You probably need to convert them to a format your burning software understands. Please search the forum and read the Streaming HOWTO for more information. You probably want to create a MPEG PS file with a MPEG2-video and a MPEG Layer 2 or 3 audio track btw.

[Reven]

Keep in mind that an aparent bug in VLC prevents you from writing mpeg1/2 at more than 25fps. Bad news if you are in North America.

[fkuehne]

@Reven: can you tell us a bit more about this bug? I've never heard about this before.

[Reven]

@Reven: can you tell us a bit more about this bug? I've never heard about this before.

In all versions I've tested (0.8.2, 0.8.4test1a), no video frames will be output during a stream/transcode if the input video source has a frame rate greater than 25fps when either the mp1v or mp2v codecs are used.

I posted about it in an earlier thread. At first I didn't know what was causing the problem - all I knew was that with some video sources I would get output, some I wouldn't. After searching through the formums and finding a reference linking this problem to the frame rate I did some more testing and found that I could not transcode any video sources with NTSC (29.97) frame rates, but had no problem with otherwise identical video sources at 25fps.

As an example, I have two versions of the same video clip captured from VHS with a Radio 9600VP VIVO:
http://members.shaw.ca/kfitzner/TestCapture.avi
http://members.shaw.ca/kfitzner/TestCapture25.avi
The first is at 29.97 fps, the second at 25. Set the streaming output to file, MPEG 1 (or MPEG_PS),mp1v or mp2v, and the first video will transcode but the second will not.

[sethg]

This seems pretty serious for North American users. I have used VLC to play back video on my computer monitor, but this sounds like it is impossible to play it back at NTSC frame rates for my TV. Is this bug being worked on for future releases?

[Reven]

This doesn't affect playback - only streaming/transcoding. VLC will play NTSC frame rates at no problem. It's only when you try and encode with the mp1v/mp2v codecs that the problem shows. The only time playback woult be affected is if you are trying to view the video at the same time you are transcoding.

[Guest]

Thanks for the reply, Reven. My guess is that what VLC calls transcoding is required for playback to anything but the computer monitor, as the .avi appears to have a native frame rate of 24fps and to watch it on a North American TV, we would need the NTSC 30fps interlaced format. I don't know exactly what the story is for DVD's. That is, do DVD players do frame rate conversion? My guess is they don't, but I could well be wrong.

[sethg]

That last post was from me. I forgot to log in!

[Reven]

My guess is that what VLC calls transcoding is required for playback to anything but the computer monitor

Not normally, no. Normal playback and streaming are totally separate in VLC. If you are playing a video, even if you are playing it to a TV output, no reencoding of the video is required. Here is a block diagram that might illustrate:

Code: Select all

|-------------| |Encoded Video| 1 |(from file, | |network) | |-------------| | /------------>>| | | | |--------------| 2 | | Video Decode | | |--------------| | | decoded (raw) | | video | | stream | / \ | play / \ stream | / \ | / \ | |--------| |------------| 3 | |Playback| |Video Encode| | |--------| |------------| | | \-------------------<<| Play Locally | |------------| |Stream Out | 4 |(to file or | |network) | |------------|

When you play a video, the input is decoded to a raw video stream. That raw video is sent, one frame at a time, to the video card. If the video card or TV output is refreshing faster than the rate at which VLC is sending video frames, then some frames will simply be repeated more than once. VLC does no frame rate adjustments to match the refresh rate of the video display device.

Encoding is only needed when you want to output the video to a network or file in a different format than the input was in. The only time playback is ever affected by the encoding bug is when you tell VLC that you want to "Play Locally" while streaming out. That is, when you are playing while also encoding. This is because when you are playing while encoding, it is not the original video that is played. The encoded video is sent to the decoder to play. So, when transcoding and playing, VLC is decoding-encoding-decoding-playing.

This bug will affect capturing when you are saving what you capture. I think this is why some people are reporting problems with capturing. Most capturing in North America is done at NTSC frame rates. So any time you are saving what you capture with the mp1v or mp2v codecs, this bug shows up.

Hope this wasn't too long winded.

[sethg]

Not at all, it's a very good explanation. So when VLC transcodes for streaming, or for output to a file, is the frame rate conversion nothing more than sampling what the current frame is, even if it was the same as the last frame? I suppose it would have to be done that way, as interpolation between frames with motion would be a horrendously complicated process. It's not like music, with only one dimension, where it is easy to change sampling rates without repeating samples.

I've tried to use the transcoding feature to take an XviD encoded stream at 24fps and create an MPEG-2 file, suitable for burning to a DVD for playing to a NTSC TV with a native rate of 30fps. I used the wizard interface, and it warns you that VLC is not good for file-to-file transcoding and recommends streaming instead. That means a second PC and is not a great solution. While I was able to wrestle it into creating the appropriate VIDEO_TS directory and .vob file, it did not create the .ifo and .buf files that applications like Roxio and Nero create. These files hold the chapter information. (See my post at viewtopic.php?p=41986&highlight=#41986)

As for why go to DVD at all, my PC is in one room and the TV in another, and I don't think that 25 feet of S-Video cable would be very good for signal quality. Perhaps it wouldn't degrade that badly with good quality cable?

If I were to set up a second PC for playback, is there any interface for an IR or RF remote to control VLC without a keyboard?

Thanks for your patience and your help.

[sethg]

I can verify your bug, Reven, with a XviD encoded input file with a frame rate of 24fps (NTSC film). I tried to transcode the video to MPEG-2 at 3Mbps with MPEG audio at 192Kbps in a MPEG_TS container and I get audio but no video in the output file. I did not specifically set the output frame rate and I don't know what the default behavior is.