List: linux-video Subject: [video4linux] Video editting From: gsstark () mit ! edu Date: 1998-08-19 23:06:27 [Download message RAW] So, a friend just came back from film school for the summer. There she used macs with two monitors and frame grabbing hardware for doing serious video editting, the software was from Avid and Adobe. She said digital video editting is great, but ``I just wish it didn't crash so much'' How far are we from actually being able to do such work on Linux? Are these frame grabbing boards up to the standards of professional systems? I'm not sure exactly what that entails, whether it's just a matter of quality or there are obscure features they need (timecodes? drop-frame stuff?) Also, I have a hardware question, can a PCI frame grabber write frames directly into the video memory of an AGP video card? greg ------------ To unsubscribe from this list send mail to majordomo@phunk.org with the line "unsubscribe video4linux" without the quotes in the body of the message.
List: linux-video Subject: Re: [video4linux] Video editting From: Alan Cox <alan () cymru ! net> Date: 1998-08-19 23:10:43 [Download message RAW] > How far are we from actually being able to do such work on Linux? > Are these frame grabbing boards up to the standards of professional > systems? I'm not sure exactly what that entails, whether it's just a > matter of quality or there are obscure features they need (timecodes? > drop-frame stuff?) No idea > Also, I have a hardware question, can a PCI frame grabber write frames > directly into the video memory of an AGP video card? Yes. AGP is just across a PCI bridge ------------ To unsubscribe from this list send mail to majordomo@phunk.org with the line "unsubscribe video4linux" without the quotes in the body of the message.
List: linux-video Subject: Re: [video4linux] Video editting From: gsstark () mit ! edu (Gregory S ! Stark) Date: 1998-08-30 18:18:18 [Download message RAW] Alan Cox <alan@cymru.net> writes: > > How far are we from actually being able to do such work on Linux? > > Are these frame grabbing boards up to the standards of professional > > systems? I'm not sure exactly what that entails, whether it's just a > > matter of quality or there are obscure features they need (timecodes? > > drop-frame stuff?) > > No idea Ok, I asked questions about what professional video editting requires. The main thing is that they need to be able to grab clibs about a minute long and capture every single frame without dropping even a single frame. I've watched a video capture program on Windoze once and it was dropping a frame every 20s or so. Assuming a bernoulli distribution that means they would have to try about 64 times on average before they would get the whole 1 minute clip without losing a frame. (It's also possible it isn't a time-independent distibution and the dropped fames were caused by a repeating feature of the NTSC signal). Was that rate of dropped frames characteristic of the hardware? Or was it due to the software or the OS? If it's typical of the hardware I suppose it would be possible to implement a grabber program which let you grab twice and synchronized the clips based on a frame by frame comparison. Also, I'm told serious work couldn't be done on-line on the computer. Anything output from the computer to VHS was too low quality and looked digitized. Is that true of this hardware too? (Instead they grabbed low-quality clips with timecodes, editted the clips on the computer, then outputted an edit decision list, which they took to a place where they did a linear tape-to-tape copy cut according to the decision list.) > > Also, I have a hardware question, can a PCI frame grabber write frames > > directly into the video memory of an AGP video card? > > Yes. AGP is just across a PCI bridge I'm not sure I understand this, I think I'll go back to my nice simple world of software. :) Actually if you could point me to some basic primer on PCI and AGP stuff, I would appreciate it. greg ------------ To unsubscribe from this list send mail to majordomo@phunk.org with the line "unsubscribe video4linux" without the quotes in the body of the message.
List: linux-video Subject: Re: [video4linux] Video editting From: Daniel Dunbar <ddunbar () diads ! com> Date: 1998-08-30 19:13:18 [Download message RAW] Gregory S. Stark wrote: > > Alan Cox <alan@cymru.net> writes: > > > > How far are we from actually being able to do such work on Linux? > > > Are these frame grabbing boards up to the standards of professional > > > systems? I'm not sure exactly what that entails, whether it's just a > > > matter of quality or there are obscure features they need (timecodes? > > > drop-frame stuff?) > > > > No idea > > Ok, I asked questions about what professional video editting requires. The > main thing is that they need to be able to grab clibs about a minute long and > capture every single frame without dropping even a single frame. no... professional editing needs continous (no burst speed stuff) capture... not 1 minute... not 2 minutes... 30 minutes or so, maybe an hour... really support has to be there for interfacing with external betacam decks, etc. for timecode and batch clip dumping. > I've watched a video capture program on Windoze once and it was dropping a > frame every 20s or so. Assuming a bernoulli distribution that means they would > have to try about 64 times on average before they would get the whole 1 minute > clip without losing a frame. (It's also possible it isn't a time-independent > distibution and the dropped fames were caused by a repeating feature of the > NTSC signal). that was probably just hardware.... i can capture 720x480 30fps with cd-quality audio w/o dropping frames under windows.... > Was that rate of dropped frames characteristic of the hardware? Or was it due > to the software or the OS? If it's typical of the hardware I suppose it would > be possible to implement a grabber program which let you grab twice and > synchronized the clips based on a frame by frame comparison. hardware... of course the fact that the software is bloated means it might take more hardware to get the correct results... but it isn't because windows has some built in unability to capture full-frame video w/o dropping frames. > Also, I'm told serious work couldn't be done on-line on the computer. Anything > output from the computer to VHS was too low quality and looked digitized. Is > that true of this hardware too? thats not really true... vhs is definatly too low quality, but lots of commercial style work is done on a nle (non-linear editer) online these days, and dumped to betacam afterwards... even film stuff is/can be edited on computer and dumped back to film. > (Instead they grabbed low-quality clips with timecodes, editted the clips on > the computer, then outputted an edit decision list, which they took to a place > where they did a linear tape-to-tape copy cut according to the decision list.) that is done a lot too... mainly for film and tv series stuff though. at the end, the main reason you can't do professional or semi-professional or really even amateur video editing under linux is because of the lack of software.... at the moment the best you can do is playback captures with xanim and maybe (tediously) edit them in gimp.... with a semi-decent software package and support among the drivers for the cards that support it for video exporting (is there such support now? i haven't seen it on any cards that i can recall) you could do at least low-end editing on linux... time will tell.... > > > > Also, I have a hardware question, can a PCI frame grabber write frames > > > directly into the video memory of an AGP video card? > > > > Yes. AGP is just across a PCI bridge > > I'm not sure I understand this, I think I'll go back to my nice simple world > of software. :) Actually if you could point me to some basic primer on PCI and > AGP stuff, I would appreciate it. > > greg > > ------------ > To unsubscribe from this list send mail to majordomo@phunk.org with the > line "unsubscribe video4linux" without the quotes in the body of the > message. -- daniel dunbar Those who dream of tachyons are ddunbar@diads.com condemned to eternal sleep. ------------ To unsubscribe from this list send mail to majordomo@phunk.org with the line "unsubscribe video4linux" without the quotes in the body of the message.
List: linux-video Subject: Re: [video4linux] Video editting From: Alan Cox <alan () cymru ! net> Date: 1998-08-30 20:06:09 [Download message RAW] > Ok, I asked questions about what professional video editting requires. The > main thing is that they need to be able to grab clibs about a minute long and > capture every single frame without dropping even a single frame. Ok the bt848 chip can do that providing you have somewhere to put the data that can keep up too. > Was that rate of dropped frames characteristic of the hardware? Or was it due > to the software or the OS? If it's typical of the hardware I suppose it would > be possible to implement a grabber program which let you grab twice and > synchronized the clips based on a frame by frame comparison. Its probably a combination of hardware constraints, software limits and OS timing ability. > Also, I'm told serious work couldn't be done on-line on the computer. Anything > output from the computer to VHS was too low quality and looked digitized. Is > that true of this hardware too? Everything I learned about image editing is that you always output and work to a higher quality than your target media. That is SVHS is the minimal input/editing media for VHS > the computer, then outputted an edit decision list, which they took to a place > where they did a linear tape-to-tape copy cut according to the decision list.) Makes sense. Keeps the images in the analog domain > I'm not sure I understand this, I think I'll go back to my nice simple world > of software. :) Actually if you could point me to some basic primer on PCI and > AGP stuff, I would appreciate it. When doing overlay or capture the BT848 does DMA transfers. PCI cards can DMA to any PCI "target" - other memory resource on the bus - that includes main system memory (capture mode), video memory (overlay). PCI bridges link multiple PCI busses together (you can only put 4 or 5 loads on a PCI bus so you end up needing a tree of them). AGP looks to PCI like a PCI bus but is a faster (133Mbytes/second) single device interface meant for video cards. The BT848 doesnt know the difference. Alan ------------ To unsubscribe from this list send mail to majordomo@phunk.org with the line "unsubscribe video4linux" without the quotes in the body of the message.