Help with how to process with AviSynth a capture with strange cadence

[rcubed]

I have a program I have captured from cable using an Intensity Pro. The cable signal is 1920 1080i 59.94. The capture is TFF. When I examine the avi file frame by frame in AviSynth I see what appears to be 1 progressive frame followed by 4 frames with what I can best describe as combed. A separate fields operation results in clean frames, but has a weird cadence due to the 1P, 4 Combed frames.

In previously seasons captures of this program series the material was clearly telecined and only required a TFM() Decimate() sequence to turn it into 23.9 progressive source that could then be encoded using HCEnc and 3:2 pulldown.

It appears they are doing something strange (by my standards) with this seasons programs and I am not sure how to handle this correctly.

Could someone supply some pointers on how to handle this or at least a pointer to info that I can read up on what I have to do. :stupid: Or a sample AviSynth script as an example would be helpful to understand the process. :thanks:

Perhaps something like Nedi is appropriate. I've been trying to follow the discussions in the forum, but I find my head spinning :confused: (I'm getting older and things just aren't as easy to understand or clear as they were 30-35 years back - I am beginning to have sympathy for how my father used to feel when I'd try to explain things from engineering work to him - or my spouse) :eek:.

People here have been most helpful in the past. Thanks in advance to anyone who can help I would really appreciate it.

rcubed

[manono]

You could have saved yourself all that typing and just provided a 10 second sample with steady movement. Or even 5 seconds if the file size is already quite large.

[rcubed]

You could have saved yourself all that typing and just provided a 10 second sample with steady movement. Or even 5 seconds if the file size is already quite large.

Manono,
I did prepare a 6 sec section processed down using Spline64Resize(960,540) with direct stream copy and the file sizd was about 400MB. A full resolution would be even bigger. Any recommendations for a site that will allow a file that large 400MB (free one preferably), or is about a 200MB one at the same resolution ok?

Thanks,

rcubed

[manono]

I don't think anyone wants a resized sample. I know I don't. I believe MegaUpload allows 400MB samples. Not that I have any interest in downloading something that large, but maybe others will. Why so big? Are you capping uncompressed?

Also, how did you manage to direct stream copy a resized AVI? It must have been reencoded uncompressed. OK then, give us 2 seconds from the untouched source. Just make sure it's the right 2 seconds.

What happens when you TFM it? All progressive with one duplicate in every 5 frame cycle?

[rcubed]

Manono,
Yes it is captured uncompressed - raw. One frame = 4MB. I'll see if I can capture it in a smaller format that shows the same pattern. I'll advise tomorrow.

rcubed

[Didée]

You could also Trim() an appropriate section with Avisynth, and reencode with x264 --tff. Since it's only for figuring the pulldown pattern, this should be sufficient. And it'll be much smaller.

[rcubed]

I don't think anyone wants a resized sample. I know I don't. I believe MegaUpload allows 400MB samples. Not that I have any interest in downloading something that large, but maybe others will. Why so big? Are you capping uncompressed?

Also, how did you manage to direct stream copy a resized AVI? It must have been reencoded uncompressed. OK then, give us 2 seconds from the untouched source. Just make sure it's the right 2 seconds.

What happens when you TFM it? All progressive with one duplicate in every 5 frame cycle?

Manano,
Yes, doing just a TFM() the result appears to be progressive with one duplicate every 5 frame cycle. I configured my cable box for 720p and did a capture of the a portion of the program and that file viewed in AviSynth, looks pretty similar to the TFM'd file when you examine them side by side in AviSynth windows. Does this mean it's as simple as doing a TFM on the file and encoding it as 29.97 progressive, or is there a better alternative. :stupid:

The 720p version has a more macroblocking than the 1080i capture. I'm not sure in what form / size the cable company broadcasts the HD programming. I had a tech out loo9king at signal level problems and he indicated the cable company is broadcasting in Mpeg-4. If I'm not mistaken the cable box is having to convert the file for display. If they truly broadcasting 1920 1080i then when you select 720p on the box it must be down converting. It is not possible to get in touch with anyone with technical expertise to answer questions about what they are doing. This tech seemed to be more informed that others.

The Intensity Pro only allows 720p and 1080i captures. Raw files are still very large at 720p

@Didee

I used the H264vfw H.264/MPEG-4 AVC codec with the default options in AviSynth to encode a small portion of the program from the 1080i capture. It is available at
http://www.megaupload.com/?d=EA7CF4BH for download and is about 6MB. Is this a satisfactory sample for what you wanted?

Thanks to everyone again for taking the time to help and for any additional info you can supply. Thanks in advance

rcubed

[Didée]

For the record, the sample is technically borked because you didn't set the switch to encode as interlaced. (Which I had implied by the "--tff" switch for the commandline x264).

But no tragedy. Fact is the source is not using the standard 3:2:3:2 pulldown pattern, but for reasons unknown uses a 4:2:2:2 pattern instead. (Perhaps somone did a frame pulldown from 24p to 30p, and pulled the fields 2:2:2:2 from that 30p.)

Technobabble aside, bottomline is that you simply load the source, do a vanilla

TFM().TDecimate()

and get the original 23.976 fps progressive film. Quite simple.

(Given that your original 1080i capture was correctly set up for interlaced compression - if not, you'll end up with bad color ghosting.)

[rcubed]

For the record, the sample is technically borked because you didn't set the switch to encode as interlaced. (Which I had implied by the "--tff" switch for the commandline x264).

But no tragedy. Fact is the source is not using the standard 3:2:3:2 pulldown pattern, but for reasons unknown uses a 4:2:2:2 pattern instead. (Perhaps somone did a frame pulldown from 24p to 30p, and pulled the fields 2:2:2:2 from that 30p.)

Technobabble aside, bottomline is that you simply load the source, do a vanilla

TFM().TDecimate()

and get the original 23.976 fps progressive film. Quite simple.

(Given that your original 1080i capture was correctly set up for interlaced compression - if not, you'll end up with bad color ghosting.)

Didee,

Sorry about the -tff issue. :stupid: I did the encode directly from within AviSynth. I don't do well with command line stuff. I type about 20 words per minute but there are 21 errors in what I actually type (getting old is a b-tch). I find check boxes a lot easier than typing. I can recognize it when I see it, but have trouble remembering the exact syntax. For AviSynth I have some canned scripts that I keep and modify as needed even then I frequently make typing mistakes when I do the mods. When you capture 1080i with the Intensity there shouldn't be any compression in the capture.

Thanks for the explanation :thanks: I've only seen the std
3:2 pulldown on sources from the cable. Now I can start freeing up some disk space by getting the files processed. This one really confused me.

Since the cable company is streaming only the stream you asked for (two way communication when you change a channel they only send that channel to your box). I'm beginning to wonder if they send the 480i, 480p, 720p or 1080i version to your box depending on the conversation between the TV and box. That would save even more bandwidth. Sometimes the source material is really good other times it is crap (bad macro blocking) not sure if they play games at the source - encode at lower bit rates or resolution for some programs and not others, or if it goes back to how the network or provider to the cable company. They could be upscaling the source material hence the loss of quality. I know they are having band width problems which is why they stopped sending all channels out all the time. As I mentioned they are very tight lipped about what they are really doing.

I really appreciate that you and people like Manomo are willing to take the time to help out with problems. I check out the forum each day to try to keep on top of things.:) Thanks again!

rcubed

[rcubed]

Hi,
I checked into the specs for the HD box my cable provider has. There is only mention of an MPEG-2 decoder in the data sheets no MPEG-4 decoder. The tech must have been in error about the cable actually transmitting MPEG-4. I believe the satellite feeds may in fact be MPEG-4.

I think I have determined the reason for the strange cadence. This week I was able to capture the live show transmission of the program. It was in fact done with 3:2 pulldown at 1080i. The previous capture I had done was from the video on demand for previous (archived) shows. Looking at the difference it sure looks to me even though they call the video on demand shows HD I actually believe they are transmitting them as 720p rather than the 1080i, and since my cable box is set to 1080i as the only output option it must have been upscaled. If so the cable box does a really bad job of converting from 720p to 1080i or was the case I saw be how software would handle it ie same kind of 4:2:2:2 result. IMHO it is misleading to advertise 720p as HD which to me is 1080i. I wonder how often they are doing this for other programs?

I had to capture the program twice to get rid of the "Emergency weather alert banners that pop up for violent rain showers expected." That kind of spoils the capture. Fortunately they run two shows on the designated and the weather alert was done by the time the 2nd broadcast was done. They also pop up a "select" to restart the program at the most inopportune time (somewhat random). Between the two captures I could splice together a "pristine" copy. (whine...whine...whine :rolleyes:)

Again thanks for the help.

rcubed