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Author Topic: Ripping festival trailer DVD to DCP (ultimately)  (Read 26946 times)

Wolfgang Woehl

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #15 on: March 20, 2012, 02:36:00 AM »
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The duration of all MXF tracks must be the same.
Check the "Duration" field for both "Picture" and "Sound". When you load an asset here these fields initially show the intrinsic durations of the selected MXF containers (which can differ, in this case probably not by much). In a composition reel both assets have to play for the exact same time, obviously. So set both values to be the same (not higher than common max though) and you're good to go.
« Last Edit: March 20, 2012, 02:37:43 AM by Wolfgang Woehl »

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #16 on: March 20, 2012, 03:56:13 AM »
Where is the "duration" field? I missed that somehow. Anyway, I got around the problem by producing an mp4 instead of the avi I had been using. Not sure why it made any difference, but there you go. Success!

I produced a DCP, and already ingested it onto the server in question. Unfortunately this was all way past closing time, so tomorrow I'll shine it on screen and check audio sync and compare resolution to the original DVD. Can't be any worse, but we'll see.

In the meantime, thank you all yet again for your help. Is there any chance that the video file-to-TIFF portion of the procedure might get its own tab within opendcp? Or also the wav extraction? I actually did split the one wav file that the command line produced into mono left and right with audacity. Otherwise, where do I put the one stereo wav file when making MXF files? Not clear on that.

walterlionguy

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #17 on: March 20, 2012, 04:36:15 AM »
Glad to hear you made progress!  Once you get the hang of it, its really not that hard to work with generating image sequences and dealing with WAV extraction/resampling.  It may seem tedious at first, but its the industry standard for pre digital cinema creation.  You could test it right now with a trial of fraunhofer easyDCP Player if you wanted to, but it's Mac/Win only.

Please keep us posted on the result when you strike an arc and check your DCP tomorrow!  :)

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #18 on: March 20, 2012, 09:11:49 PM »
Oh, well... so much for that. The image is perfect. I would swear it looks better than on the DVD, but I don't know how that is possible.

The audio, on the other hand... not so much. Sound like a basso profundo space alien talking, like a tape deck where the tape would get stretched out, or the deck's motor was going bad. Sounds slow and low, and slightly garbled.

I listened to both wav files I produced with audacity, and they sound great. The "left" wav track only comes out the left speaker (or headphone) and the "right" only out the right. What gives? Any clues?

If I use just the one wav track that is produced from the command line that Terrence posted (rather than producing discreet left and right,) where do I place it when selecting files to create the MXF? just on the left, right or both?

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #19 on: March 20, 2012, 10:21:06 PM »
Wait a second... if each wav file is only playing out of one channel, then they are not, in fact, mono, but rather stereo with (effectively) a muted second channel. Correct? Could this be the cause of the problem? Does each absolutely need to be mono?

walterlionguy

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #20 on: March 21, 2012, 05:12:16 AM »
Each WAV file must be entirely mono, meaning no left/right channels in one file (muted or not).  You play one of the files, and it should come out of both left+right speakers.  If you play your left WAV and you are hearing sound from the left speaker only, and the opposite is happening with the right file, your WAV files are wrong (meaning they contain a second channel).  Try correcting this, and then make a new DCP to see if this resolves the issue.

Keep us posted!  :)

Edit: To answer your question about plugging in the WAV files into OpenDCP, both left and right parameters must each point to separate mono files, again which contain one channel each.  The same principal applies to 5.1 or 7.1 DCP's.
« Last Edit: March 21, 2012, 05:22:44 AM by walterlionguy »

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #21 on: March 21, 2012, 03:57:25 PM »
Success! I corrected the issue with audacity, splitting the stereo into mono channels, rather than into left and right as before. Sound is very good, but it does appear to be lagging slightly behind the picture, a few frames maybe, but noticeable. Anything to be done about this? What could be causing this problem? Normally I associate this with progressive scan options when ripping and encoding, which I try to avoid.

Also, how do you guys produce your mono wavs? I take it there's no problem with using audacity, so long as the wavs are of equal length to each other and to the image file, correct?

walterlionguy

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #22 on: March 21, 2012, 05:03:55 PM »
Believe it or not, iv never had a need to convert a DVD to DCP yet, only converted blu-ray and blu-ray 3D to 2D/3D DCP's.  With blu-ray you can use eac3to to extract the DTS-HD Master or Dolby Tru-HD 5.1/7.1 into mono WAV's, and then change the length accordingly to match 24fps.

Also, is the audio as a whole lagging behind the picture from beginning to end?  That alone would be a sign of extra blank space appearing in the picture or audio.  Or does it fall out of sync as the DCP plays?  Did you change the length of the audio? (remember this step must take place!)  If you forget this, when you take your 23.976fps NTSC dvd and convert it to 24fps, the video will end up appearing on screen faster than the audio, noticeably more so as the movie progresses.  When you say lagging slightly behind picture, I am assuming you mean the picture appearing, and the audio playing (lagging) after.

Can you provide us with the complete frame count of your DCP?  I can then give you an Hour/Min/Sec time calculation that your audio must be for 24fps playback.

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #23 on: March 21, 2012, 09:33:20 PM »
Did you change the length of the audio? (remember this step must take place!)  If you forget this, when you take your 23.976fps NTSC dvd and convert it to 24fps, the video will end up appearing on screen faster than the audio, noticeably more so as the movie progresses.  When you say lagging slightly behind picture, I am assuming you mean the picture appearing, and the audio playing (lagging) after.

Can you provide us with the complete frame count of your DCP?  I can then give you an Hour/Min/Sec time calculation that your audio must be for 24fps playback.
Whoa, whoa, whoa... nobody ever told me this! I didn't sign up for this!

Kidding. OK, so can someone point me to the description of audio length and why it need to be modified? Yes, the picture appears, the guy's mouth opens, and a few frames late his words come out. Sadly I already deleted that projects tiff, j2k and audio files so as to free up space for the longer version of the same festival's trailer, this one with an added sponsor or something. Let's see if it happens again to this one.

Is it definitely going to happen if I don't modify the length of the wav? I thought the wav and the image file(s) had to be exactly the same length, and if they weren't the process couldn't move forward. Being that it did proceed, they must have been the same length, QED. No?

Edit: Just to get this out ahead of time, this next trailer I'm working on is 27,337 frames (or TIFF images, at least.)
« Last Edit: March 21, 2012, 09:41:17 PM by hdvprojection »

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #24 on: March 22, 2012, 12:50:36 AM »
OK, this only appears to be working with mp4 files. I tried an avi and a vob, and with both there was an incongruity with the length of the mxf files produced. Perhaps the command line I'm using from Terrence's post only applies to mp4s, I'd have to assume.

Edit: the total frames from the mp4 I'm using is 27,355.
« Last Edit: March 22, 2012, 01:28:30 AM by hdvprojection »

walterlionguy

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #25 on: March 22, 2012, 05:21:36 AM »
Quote
OK, so can someone point me to the description of audio length and why it need to be modified?

You have content that is 23.976fps originally, and your manually making an image sequence out of it.  You must change the speed of the audio accordingly that you extracted as the video plays slightly faster in your DCP compared to the dvd.  The audio speed needs to be changed so it can properly match up with the new 24fps video.

Quote
Yes, the picture appears, the guy's mouth opens, and a few frames late his words come out

Although the above step is something you must do, if you do forget it, the sound should not immediately be out of sync, it should very slowly fall out of sync.  If the sound is immediately delayed there is probably blank space at the beginning of your audio files.  This may have something to do with the program (audacity) that you used.  Make absolute sure that its an identical copy of the audio which came out of your mp4 file, and then change speed once you confirm that.  Also, double check that your image sequence frame count is exactly equal to the frame count in the mp4, as they must match.  I think its unlikely that frames were dropped when you made the image sequence, but we need to be sure.

27,337 frames @ 24fps = 1139.0416 seconds, or... 18min 59.0416 seconds
27,355 frames @ 24fps = 1139.7916 seconds, or... 18min 59.7916 seconds.  Round off to the closest number possible that your editor allows.

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #26 on: March 22, 2012, 06:46:19 AM »
OK, then, so theoretically this next one is going to be waaaaaaayyyy off, since it starts with a fifteen-minute slide show (no sound) before going into more or less the same video as the first one, where I could just notice the lag.

So, am I clipping a certain amount from the front of the wav, then stretching the remainder? If so, what's a good way to do that? Audacity (plus a calculator) will do, I hope?

walterlionguy

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #27 on: March 22, 2012, 05:16:45 PM »
Just making sure, but when changing the length of your WAV's, you have to change the file as a whole (your making the sound play slightly faster) to get the different length.  You cannot just clip/ad sound from the beginning or end too match your desired length.

Assuming you did a frame count check with the MP4 + your image sequence, and they showed up the same, I would promptly dump whatever tools you are using to extract/modify the WAV's.  Try finding an alternative.  Its a very straight forward process and I think one of the programs you are using is messing around with them.  If you properly extract it straight from your MP4 file (which plays fine) and change the length to suit 24fps playback, it will work if done properly, guaranteed.

hdvprojection

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #28 on: March 22, 2012, 06:28:30 PM »
There's something I'm not getting. Opendcp will not allow me to create a DCP from MXFs that do not match up lengthwise. If the WAVs I'm producing are, say, 18:59 and the J2Ks add up to 18:59 in their respective MXFs, then... ? How are they winding up out of sync?

Mind you, I had to leave work last night without completing the second, longer version of the trailer, so for all I know it's going to be perfectly fine. Also, I should check the MP4 I produced from the VOB, to see if that's where the issue is arising. Otherwise it doesn't make sense to my brain.

Terrence Meiczinger

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Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #29 on: March 23, 2012, 12:33:59 AM »
All durations (frame count) MUST be the same per DCI specifications. While their duration may be the same in seconds, they may have a different number of frames. This is could happen because you created an audio MXF at 25fps and the picture MXF at 24fps. However, more likely, it's because the duration of your audio was a frame or two longer or shorter than the video. This is common, because most editing packages don't enforce your audio duration to equal your video duration. If your editing packages allows you to view in frame, you'll likely see the difference. The same is true for formats like MP4, they don't enforce audio/video to frame align. In any case, it is not a big issue and you can adjust for this in the GUI. Just reduce duration of the whichever is longer.

dcinemaforum.com

Re: Ripping festival trailer DVD to DCP (ultimately)
« Reply #29 on: March 23, 2012, 12:33:59 AM »