Timecode difference

[SameSelf]

When I push video through the following script (edited for brevity):

DirectShowSource("D:\ntsc_dv.avi").AssumeFPS(30000,1001)
AssumeBFF
ConvertToYV12(interlaced=true, matrix="PC.601")
QTGMC( Preset="Slow", EdiThreads=8 )

and

ffmpeg -i script.avs -vcodec copy -acodec copy deint.avi

Then, bring the de-interlaced 59.94 fps footage back into PP, the de-interlaced footage timecode is always exactly two frames shorter than the source footage timecode. Shouldn't they be the same? I have the PP settings set to 59.94 Drop-frame, versus 59.94 Non-drop frame. Arggh, this timecode stuff is so confusing!

Can someone please explain this to me? Thanks!

[poisondeathray]

DirectShowSource can have problems with frame accuracy. Try AVISource instead

How many frames are there 1) with info() for your script ; and in 2) premiere with the native AVI, and 3) premiere with the processed AVI ?

You can intpret the footage in PP, if the framerate is "off", but the framecount is what is important

[smrpix]

Are the videos actually different lengths or is it simply seeing the difference in how DF/NDF counts? How long is your clip?

[SameSelf]

DirectShowSource can have problems with frame accuracy. Try AVISource instead

How many frames are there 1) with info() for your script ; and in 2) premiere with the native AVI, and 3) premiere with the processed AVI ?

You can intpret the footage in PP, if the framerate is "off", but the framecount is what is important

Oh bummer. I knew this would come back to bite me. For some bizarre reason, AVISource gives an error which is why I was forced to use DirectShowSource. So it wasn't by choice sadly.

I need to look more closely at the frame count and see if it lines up and the timecode is the problem.

[poisondeathray]

What error does avisource give ? directshowsource is always the last resort

[SameSelf]

I will post back later with the exact message. IIRC, it was some unable to open file message like there was a problem with the AVI.

EDIT: Thanks for the help. I definitely want to get this fixed so will post back later with the exact details in terms of the error, frame counts, etc.

[smrpix]

Just line both clips up in PP, zoom in on the tail and see if they're different. If they are, pick a spot in the middle of the timeline, mute and unmute the top video track and see which direction they're different.

[SameSelf]

Here is the error code when I try to use AVISource which is Line 2:


FWIW, here is the Mediainfo. So I am not exactly sure what it is complaining about. It doesn't like the dvsd fourcc?

General
Complete name                            : D:\Video\Library\Batch\Tape3.1.1.avi
Format                                   : AVI
Format/Info                              : Audio Video Interleave
Commercial name                          : DV
File size                                : 181 MiB
Duration                                 : 50s 117ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 30.3 Mbps

Video
ID                                       : 0
Format                                   : DV
Codec ID                                 : dvsd
Codec ID/Hint                            : Sony
Duration                                 : 50s 117ms
Bit rate mode                            : Constant
Bit rate                                 : 24.4 Mbps
Encoded bit rate                         : 28.8 Mbps
Width                                    : 720 pixels
Height                                   : 480 pixels
Display aspect ratio                     : 4:3
Original display aspect ratio            : 4:3
Frame rate mode                          : Constant
Frame rate                               : 29.970 fps
Standard                                 : NTSC
Color space                              : YUV
Chroma subsampling                       : 4:1:1
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Bottom Field First
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 2.357
Time code of first frame                 : 00:00:46;05
Time code source                         : Subcode time code
Stream size                              : 172 MiB (95%)

[SameSelf]

According to vdub, the original AVI is 1503 frames (Frame: 0 of 1502, so I guess zero must be counted) which translates to the following DF timecode in PP: 00;00;50;02. The de-interlaced version is 3006 frames (Frame: 0 of 3005) which on inspection looks like the correct number of frames, but PP interprets the length with the following DF timecode: 00;00;50;05.

When I drop the original AVI into a timeline, the video ends at 00;00;50;03. When I drop the deinterlaced video into the timeline it ends at 00;00;50;05. These extra couple of frames seem to be independent of the length of the footage. In other words I have other clips that are much longer that exhibit the exact same difference in timecode.

[poisondeathray]

You can use cedocida for a VFW DV codec

DV-AVI is very stable and consistent in premiere, and all editors - it's unlikely something is actually wrong

Did you setup the sequence settings correctly ? For example, if you have a 30.0 FPS sequence you will get 00;00;50;03 instead of 00;00;50;02 with the same video

However, both single and bobbed versions should be the same length on the same sequence - so something is wrong for that

Did you look at the frames as smrpix suggested? That should tell you what is going on

You check each stage to see where it went wrong, just go step by step. If the avs is correct, has the correct number of frames, then how many frames does deint.avi have, according to vdub or avisynth info() ? eg did ffmpeg screw up , or was is a dss error and not ffmpeg's fault? (ie try avisource)

Another way to debug is to do tests with an overlay like info() and/or showframenumber() and hardcode on to see where the problem is

[SameSelf]

Sorry I was not specific enough before. Please let me restate, "According to Avisynth Info() as displayed in vdub, the original AVI is 1503 frames..." and so on as stated above.

Thanks for the cedocida suggestion. I had not heard of that before and will give it a try.

As for my settings in Premiere, as far as I can tell, it is set up correctly. I will go back and look again though to make sure. This happens enough that I need to get it resolved. It has been a problem in the past, just never cared enough to try to figure out what was going on.

I will try the other suggestions, like that of smrpix and showframenumber() overlayed, when I get some time. Thanks so much. Been pretty busy, so finding time to troubleshoot is tough. But I appreciate all the help. I now have some more tools.

[ndjamena]

Could there be a negative delay in the audio skewing the timecodes?

AVI doesn't have proper delays, it just fills the empty space with junk, and I know FFMPEG tends to add negative delays to PCM (grrr).

[SameSelf]

Could there be a negative delay in the audio skewing the timecodes?

AVI doesn't have proper delays, it just fills the empty space with junk, and I know FFMPEG tends to add negative delays to PCM (grrr).

The audio doesn't worry me because I can just drop the audio of the original clip into the timeline. So tbh I am not even sure what ffmpeg is doing to the audio because I don't use it.

But if you are saying that the audio might be the source of my problems, that is a good suggestion. I will try ffmpeg with -an.