|
|
| SHDBengBu |
| Posted: Feb 28 2012, 02:31 AM |
 |
|
Newbie
Group: Members
Posts: 4
Member No.: 34358
Joined: 27-February 12
|
Hi, I'm new at using VD or any other software of that kind.
When I capture my miniDV videos, recorded (and now used for the capturing) by a Sony DCR VX700E, build in 1996,
I see that the raw AVI file has a video compression of ~8.6. The 'raw' video captured has a lot of compression-, interlacing- and quantization artefacts.
(I wanted to add a screenshot here, but don't know how)
The data of the captured AVI-file are as follows:
Frame size: 720x576, 25.000 fps(40000ys)
Length: 8171 frames (5:26.84)
Decompressor: Internal DV decoder (dvsd)
Number of key frames: 8165
Min/avg/...frame size: 144000/...(1148204K)
Min/avg/.... delta frame size: 0
Data rate: 28779 kbps (0.02% overhead)
Im using firewire to connect my Sony with my notebook.
I have read that the compression is a hardware compression inside the Sony. Is that true?
Is it possible to decompress the video to get rid of the artefacts? How would I do that?
Or are my settings wrong?
I'm asking because I think that the raw file with such strong artefacts can't be fixed by using filters (that's at least the result of my tries).
I have tried to ad different filters (e.g. bob doubler, deinterlace) and tried to compare the results with different settings, but that is very difficult for an inexperienced person like me.
Maybe somebody knows which filters and settings are best for my equipment. I want to cut the videos as raw files and convert it later to MP4 (H.264).
I'm using VD 1.9.11 and have tried to use the 'VD Help' but I can't find the filters described there.
Is there a new description of the filters?
Thanks for your help in advance.
SHDBengBu
|
|
| SHDBengBu |
| Posted: Feb 28 2012, 02:49 AM |
|
|
Newbie
Group: Members
Posts: 4
Member No.: 34358
Joined: 27-February 12
|
Hi,
I just found the description of the filters inside the ‘Add Filter’ window. But it is still difficult for me to understand and to chose the right settings.
SHDBengBu |
|
| SHDBengBu |
| Posted: Mar 5 2012, 09:53 AM |
|
|
Newbie
Group: Members
Posts: 4
Member No.: 34358
Joined: 27-February 12
|
Ok, since I got no answer from the specialists, I will give them myself (please correct me if I’m wrong)!
The compression inside the dv-cam is around 8.6 (compression mode: internal DV decoder (dvsd)) which leads to a file size (60 min video) of ~13Gbyte (see below).
The pixels per frame = 720 * 576 = 414,720
Bits per frame with a colour depth of 24bit = 414,720 * 24 = 9,953,280 = 9.95Mbits
Bit rate at 25 frames per sec. (25fps) = 9.95 * 25 = 248,83Mbits/sec
Video size for 60min (8bit=1byte) = 248,83Mbits/sec * 3600sec = 895,795.2Mbits = 111,974.4Mbytes = 111.9744Gbytes / 8.6 compression = 13.02 Gbytes
The decompression of the file is as well possible (save it as raw-file without compression), but it makes no sense because all the artefacts will still be there since it got captured from the dv-cam like that and the file size would be huge!
I found, capturing the same video several times, that the artefacts are not always there or not always at the same place. That means that the reason is my old dv-cam! Now it is possible to cut the different good sections together and get a better result.
Since I could not figure out how to save the captured file as mp4 (H.264), I just modify it with the deinterlace filter, compress it to DV (using ffdshow) and save it as an .avi file (the size and the compression mode (dvsd) is the same as before which means that there is no compression loss).
To change it to an mp4 file I use the free “Any Video Converter” with a bit rate of 2048 kbps which leads to a file size reduction factor of ~14. That means my final 1h movie has less than 1Gb size (before 13Gb).
That’s it.
Best wishes
|
|
| phaeron |
| Posted: Mar 11 2012, 09:33 PM |
|
|
Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
|
| QUOTE | | Since I could not figure out how to save the captured file as mp4 (H.264), I just modify it with the deinterlace filter, compress it to DV (using ffdshow) and save it as an .avi file (the size and the compression mode (dvsd) is the same as before which means that there is no compression loss). |
Ack, no, this isn't true!
Video compression works by dropping information from the video that the eye doesn't perceive much. In other words, when your camera originally compressed the video into DV, it threw away bits until the result fit within 25Mbits/sec. You're making two assumptions here about your second compression pass:
- That the same bits are thrown away again.
- That the deinterlace operation hasn't added new bits.
In practice, you're going to lose a bit of quality on both. The codecs you use for compression often aren't perfect and you're not guaranteed that if you compress the same video each time that it produces the same result. Your deinterlace operation also shuffles around some data in a way that doesn't quite fit DV -- DV is designed around storing interlaced video -- so you're likely going to get some compression artifacts there. What you really want is to avoid going through a lossy format again, and that involves using a lossless format like Huffyuv or finding a way to export the deinterlaced video directly to the encoder without going through a file.
Now, the fact that you are seeing different artifacts on multiple plays of the same tape is a bad sign. It means that the artifacts are not from the DV compression itself but are errors from reading the tape. DV has error detection and concealment mechanisms that try to hide this, but these errors produce artifacts that are much worse than those that are from the DV compression itself. I'd try to find a way to get a cleaner read for the tape first, perhaps by cleaning the heads and doing some trial runs on a fresh tape before re-playing the video again. |
|
|
