Re: [mythtv-users] HDTV to DVD w/o decode and encode
Rob, how are you transcoding your files down? I've been trying to figure out how to do this with my system using nuvexport. Whenever I try to transcode an HD broadcast to DVD using nuvexport it goes at like 1fps! There are some 9million frames, I calculated it would take several months to make a DVD. Unacceptable. :) I have similar hardware, 90nm 3000+ frontend/backend. I also tried making a test DVD from a Wheel of Fortune episode using the HowTo on mythtv.info: http://mythtv.info/moin.cgi/ArchiveRecordingsToDvdHowTo When the DVD was done I could play it in my computer but not on my DVD player. I'm lost. Someone please help. -Greg On 5/14/05, Robert Tsai [EMAIL PROTECTED] wrote: On my AMD64 3500+ 90nm (2.2GHz) CPU (combined frontend/backend system), mythtranscode transcodes my HD recordings to MPEG-4 (a variety of resolutions from 720x480 up to 960x540) at approximately real-time (e.g., 1 hour to transcode a 1-hour recording), in the background, while other stuff is competing for CPU/disk resources (watching other HD recordings, recording other HD broadcasts). I've never transcoded to RTjpeg/MPEG-2, so I don't know if it is harder or easier to transcode to than to MPEG-4. This is just a data point for what Linux/mythtranscode can do with a CPU similar to yours. --Rob ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
On Sun, May 15, 2005 at 02:42:53PM -0600, Greg Grotsky wrote: Rob, how are you transcoding your files down? For transcoding HD: - In the recording profiles, check the automatically transcode checkbox. All the other stuff in the profile is ignored, since no encoding is performed for HD capture. - Set up your desired transcoding characteristics in the From MPEG-2/RTjpeg transcoder (HD capture is MPEG-2); resolution, bitrate, etc.. The other transcoder will not be used. The caveat of this basic functionality is that *all* your HD shows will be transcoded in the same way. You can control whether or not your HD shows get automatically transcoded by assigning the schedules to different recording profiles (Default, High Quality, etc.). I have a patch to allow selection between multiple transcoders for HD content (e.g., high quality, medium quality, low quality), and have been using it in my own system for quite some time. It hasn't been committed to CVS yet. If you're feeling adventurous: http://www.gossamer-threads.com/lists/mythtv/dev/129254 This is how I determined that HD transcoding ought to be do-able in a little over 1x real-time with my system characteristics. --Rob signature.asc Description: Digital signature ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
--- Brad Templeton [EMAIL PROTECTED] wrote: While it is possible, in theory, to write a re-encoder that takes advantage of compression hints learned from the original encoding, that sounds like a lot of work for a rare task just to save some CPU, and CPU is cheap in such instances anyway. Thank you for the thoughtful reply, Brad. The CPU power in this case is not insubstantial. It took over 7 hours of processing to transcode the two hour movie down to a 720x480 DVD. That was on a 3000MHz AMD-64 Windoze machine running Nero Video Express. If I had an adequate solution on my mythbox, i.e. one that could be used effectively with only console I/O, I could have used my P4 HT processor for a bit quicker transcoding. But I doubt the difference would have even been 2:1, so it would still be horrifically slow. (The console I/O requirement comes from the fact that the mythbox uses the HDTV as its primary monitor so I have to use ssh to do anything outside of Myth.) We're also rapidly moving to a time when we won't want traditional DVDs. They are small and low-res, and mp2 isn't nearly as good as mp4. Plus, since all of us have computers connected to our TVs, and soon more and more people will, going to the player's restricted format becomes less appealing. I guess I just have more primitive friends! Not one of my friends has a myth box, nor even a computer hooked to a TV. Some have computers at home, but none would want to watch a show (particularly one that emphasizes the soundtrack) on their PC. Everybody has DVD players. Do I see the market changing? Yes, but very VERY slowly. Remember the YEARS it has taken to get DVDs accepted to the point that VCRs are considered obsolete. It will be five years or longer before HD-DVD players are commonplace. It's a sad fact, but it's faster and easier to record things on my Tivo and transfer to videotape than it is to make a DVD of a MythTv broadcast. Or I could just tape it on the obsolete VCR for even faster access. It's somewhat a letdown. __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
On Sat, May 14, 2005 at 03:18:34AM -0700, Joe Barnhart wrote: While it is possible, in theory, to write a re-encoder that takes advantage of compression hints learned from the original encoding, that sounds like a lot of work for a rare task just to save some CPU, and CPU is cheap in such instances anyway. Thank you for the thoughtful reply, Brad. The CPU power in this case is not insubstantial. It took over 7 hours of processing to transcode the two hour movie down to a 720x480 DVD. That was on a 3000MHz AMD-64 Windoze machine running Nero Video Express. If I had an adequate solution on my mythbox, i.e. one that could be used effectively with only console I/O, I could have used my P4 HT processor for a bit quicker transcoding. But I doubt the difference would have even been 2:1, so it would still be horrifically slow. (The console I/O requirement comes from the fact that the mythbox uses the HDTV as its primary monitor so I have to use ssh to do anything outside of Myth.) On my AMD64 3500+ 90nm (2.2GHz) CPU (combined frontend/backend system), mythtranscode transcodes my HD recordings to MPEG-4 (a variety of resolutions from 720x480 up to 960x540) at approximately real-time (e.g., 1 hour to transcode a 1-hour recording), in the background, while other stuff is competing for CPU/disk resources (watching other HD recordings, recording other HD broadcasts). I've never transcoded to RTjpeg/MPEG-2, so I don't know if it is harder or easier to transcode to than to MPEG-4. This is just a data point for what Linux/mythtranscode can do with a CPU similar to yours. --Rob signature.asc Description: Digital signature ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
On Wed, May 11, 2005 at 01:45:33AM -0700, Joe Barnhart wrote: Thanks for your response, Scott. I'd really like to see a good description of the MPEG2 format and its variations (PS, ES, TS, etc.). Even if the translator has to decode the macroblocks, wouldn't it still save time if it could use the same key frames and not have to choose the frames from scratch, like encoders normally do? The transport stream encodings are just wrappers and not relevant to your question. While it is possible, in theory, to write a re-encoder that takes advantage of compression hints learned from the original encoding, that sounds like a lot of work for a rare task just to save some CPU, and CPU is cheap in such instances anyway. We're also rapidly moving to a time when we won't want traditional DVDs. They are small and low-res, and mp2 isn't nearly as good as mp4. Plus, since all of us have computers connected to our TVs, and soon more and more people will, going to the player's restricted format becomes less appealing. I know your friend wants to watch it on his TV. Most would probably say it's easier to either eat the CPU to make it, or tell your friend to watch the disk on a computer at much higher quality than it would be to to write such a complex mpeg re-encoder for a dying format. ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
--- Scott Alfter [EMAIL PROTECTED] wrote: What you're asking is impossible; MPEG doesn't work that way. The only lossless manipulation of MPEG data that might be possible would be to crop the frame to a smaller size (you would need to crop by multiples of 16 if you were to do this) or rotate the entire frame a multiple of 90 degrees. MPEG video gets coded in macroblocks of (typically) 16x16 pixels. To scale the video, you would have to decode the macroblock, scale it, and create a new macroblock. For shrinking from HDTV to DVD, each new macroblock would pull data from several macroblocks in the original video. Thanks for your response, Scott. I'd really like to see a good description of the MPEG2 format and its variations (PS, ES, TS, etc.). Even if the translator has to decode the macroblocks, wouldn't it still save time if it could use the same key frames and not have to choose the frames from scratch, like encoders normally do? I'm not above trying to create something myself to do this task. But I'd need more information on the internal structure of MPEG2 files. I've done a couple of googles, but hard information on the MPEG2 file structure seems to be a little scarce. I know there are ISO standards I can buy for some outrageous price (something like $70 ea. for nine standards). I just can't believe it's so difficult to get a broadcast HDTV show onto a regular DVD. Yahoo! Mail Stay connected, organized, and protected. Take the tour: http://tour.mail.yahoo.com/mailtour.html ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
[mythtv-users] HDTV to DVD w/o decode and encode
I'm not alone in my search for a decent tool to archive shows originally broadcast on HDTV onto DVD media for keeping or sharing with others. For example, I'm not an Elvis fan, but my friend is and I want to give her a DVD of the recent broadcast she missed. The show is about 16G bytes in its original 1080i presentation. There is a simple scaling relationship between the original format (1920x1080 MPEG2-TS) and the desired format (720x480 MPEG2-PS). Why is there no program that takes one MPEG2 stream and scales it by a simple fraction, without decoding and re-encoding the MPEG structure? Assuming that the network took some care in encoding the MPEG file for HDTV broadcast, why not keep all the same B frames, I frames, and whatever -- and just scale everything by 3/8 horizontally and 4/9 vertically to get the required DVD resolution? I have used currently available tools to create a DVD, but with unacceptable difficulty and mediocre results. The best I've found so far is using tools under Windows to process the file -- HDTVtoMPEG2 to strip the TS into an MPEG file and Nero Vision to transcode it to DVD format. Running these on the Elvis program resulted in 6 hours of computer time and produced a DVD that has chapters every 2GB that cause the player to stop cold. Nero seems to do a complete decode/re-encode which is what takes all the time. There has to be a better way than this! Has anyone seen a software solution (preferably Linux based, open source) that scales MPEG data without decoding and re-encoding? __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] HDTV to DVD w/o decode and encode
Joe Barnhart wrote: I'm not alone in my search for a decent tool to archive shows originally broadcast on HDTV onto DVD media for keeping or sharing with others. For example, I'm not an Elvis fan, but my friend is and I want to give her a DVD of the recent broadcast she missed. The show is about 16G bytes in its original 1080i presentation. There is a simple scaling relationship between the original format (1920x1080 MPEG2-TS) and the desired format (720x480 MPEG2-PS). Why is there no program that takes one MPEG2 stream and scales it by a simple fraction, without decoding and re-encoding the MPEG structure? What you're asking is impossible; MPEG doesn't work that way. The only lossless manipulation of MPEG data that might be possible would be to crop the frame to a smaller size (you would need to crop by multiples of 16 if you were to do this) or rotate the entire frame a multiple of 90 degrees. MPEG video gets coded in macroblocks of (typically) 16x16 pixels. To scale the video, you would have to decode the macroblock, scale it, and create a new macroblock. For shrinking from HDTV to DVD, each new macroblock would pull data from several macroblocks in the original video. _/_ / v \ Scott Alfter (IIGS( http://alfter.us/Top-posting! \_^_/ rm -rf /bin/ladenWhat's the most annoying thing on Usenet? ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
