Compression level: I cant get it again with the same video.

[DogDay]

Hi everybody!

This is my first post. I would like to share with you this:

Here is a video. It is the original video, captured with a phone mobile and copied to my PC: https://mega.co.nz/#!MAJhHSRD!CP-T2IfuKpzhgRRYBMqolHzW4dLQKAnWnEvdPLEkxYY (44,7 Mb)

I work with Windows XP 32bits and encoded it with Virtual Dub 1.10.4(build 35491) x264vfw codec. Im almost sure I used default settings, just changing Ratefactor from 23 to 25. I added the internal filter 'resize' to resize the video to 50%. And I used mp3 for encoding audio.

So I get this other video: https://mega.co.nz/#!FUwyVIyK!xgzvhZzM7mpAWD7yLUZYzk13T6LPjCEt2lP9JvSuPwU (2,92 Mb)

I was very surprised with the compression ratio and the quality. But I thougth about the video, almost blue sky all the time and I thought it was possible that ratio and quality because of this.

Ok. The big problem is that I am not able to generate again this video with this compression and this quality. No matter wich params I modify i cant get the same result.

I have noticed that the compressed.avi has 25fps. And original.avi has 29,6fps. Other compressed videos I generated have 296fps!!!!!!.

Could this be the problem? How and where was modified the frame rate? I dont rememeber I changed it. And I dont know where is the option.

Could you help me, please?

Thanks in advance.

[hech54]

I was very surprised with the compression ratio and the quality. But I thougth about the video, almost blue sky all the time and I thought it was possible that ratio and quality because of this.

What?

[DogDay]

What?

Perhaps Im completly wrong, but anyway I think that is not relevant with the problem, is it?

[jagabo]

MediaInfo shows all the x264 settings that were used on your compressed video -- looks like the medium preset at CRF=25. Yes, large areas with little detail (or no motion) compress much better than more complex video. And fewer frames per second requires less bitrate.

[El Heggunte]

This forum accepts attachments as big as 500MB, therefore please, next time DO NOT upload your sample files to filesharing services unless that's absolutely unavoidable.

FWIW: the new megaupload still is designed by incompetent programmers,
and even Mediafire is being bewitched by the pink side of the Force as well u_u

[DogDay]

MediaInfo shows all the x264 settings that were used on your compressed video -- looks like the medium preset at CRF=25. Yes, large areas with little detail (or no motion) compress much better than more complex video. And fewer frames per second requires less bitrate.

Thank you so much jagabo. So static or not color complex scenes have impact in compression ...

The thing now is why compressed video is 25fps if original is 29,6? Where can that be changed? I didnt changed anything. And I am looking everywhere in the encoder options and cant see anything related to fps.

So sorry El Heggunte. Next time I will upload the files here as you suggested.

[jagabo]

So static or not color complex scenes have impact in compression ...

Anything that causes sequential frames to be different increase the bitrate requirement. Noise (CCD noise, film grain), flashing lights, flickering fire, wavy water, billowing smoke/fog, etc. Also, the more detail, and the brighter the video, the more bitrate is needed.

The thing now is why compressed video is 25fps if original is 29,6? Where can that be changed?

VirtualDub: Video -> Frame Rate... But changing your 30p video to 25p is just going to make it jerky -- 5 little jerks per second.

[DogDay]

VirtualDub: Video -> Frame Rate... But changing your 30p video to 25p is just going to make it jerky -- 5 little jerks per second.

So how will I have been able to encode the video without been jerky and without loosing audio sync at 25 fps if I havent touched those options at all?

Im really confused.

[jagabo]

I don't know what you did but your compressed video is missing every 6th frame. Ie, ~30 fps was converted to 25 fps by discarding every 6th frame.

[smrpix]

Your original is variable frame rate -- so there may or may not be a correct constant frame rate setting -- different phones and cameras handle it differently. Variable frame rate video is a pain to work with, as you have discovered.

[DogDay]

I don't know what you did but your compressed video is missing every 6th frame. Ie, ~30 fps was converted to 25 fps by discarding every 6th frame.

Thank you very much. After another round of 'try-error' I got a similar compressed video. I have had to change frame rate to 25fps. I really dont know where and why it was changed first time.

Your original is variable frame rate -- so there may or may not be a correct constant frame rate setting -- different phones and cameras handle it differently. Variable frame rate video is a pain to work with, as you have discovered.

Thank you too. I will consider this for next videos. Before compressing I will take a look to this.

[jagabo]

I don't know what you did but your compressed video is missing every 6th frame. Ie, ~30 fps was converted to 25 fps by discarding every 6th frame.

Thank you very much. After another round of 'try-error' I got a similar compressed video. I have had to change frame rate to 25fps. I really dont know where and why it was changed first time.

Your original is variable frame rate -- so there may or may not be a correct constant frame rate setting -- different phones and cameras handle it differently. Variable frame rate video is a pain to work with, as you have discovered.

Thank you too. I will consider this for next videos. Before compressing I will take a look to this.

Previously I was working with your video using ffmpegsource in AviSynth. That was delivering an average frame rate of ~29.7 fps. Today when I opened the MP4 file directly with VirtaulDub (using the DirectShow source filter) it returned 25 fps and every 6th frame was missing. The behavior of a DirectShow source filter will vary depending on what DirectShow filters you have installed.

[DogDay]

Previously I was working with your video using ffmpegsource in AviSynth. That was delivering an average frame rate of ~29.7 fps. Today when I opened the MP4 file directly with VirtaulDub (using the DirectShow source filter) it returned 25 fps and every 6th frame was missing. The behavior of a DirectShow source filter will vary depending on what DirectShow filters you have installed.

I understand you are talking about if Im ussing ffDshow or other and the version of ffDshow Im using ... Is this correct?

Or are you talking about the version of the plugin for Virtualdub here: http://forums.virtualdub.org/index.php?act=ST&f=7&t=15093& ?

[jagabo]

There are two issues: how VirtualDub gets access to A/V files it doesn't natively support, and how Windows gets access to A/V files it doesn't natively support.

Since VirtualDub doesn't natively support MP4 files it needs a plugin to open them. There are at least three input plugins for VirtualDub that can open MP4 files: DirectShow, ffmpeg, MPEG-4. I used the first of those three, the one you linked to in your last post. That gives VirtualDub the ability to open any A/V file that Windows' DirectShow (a modular, extendable API for dealing with audio and video, the system used by Windows Media Player) can open. When you open a video file in VirtualDub you can specify which source plugin to use via the "Files of type" pulldown on the Open Video File dialog. If you don't specify which to use, and you have multiple plugins that can open MP4 files, VirtualDub will pick one for you.

But Windows' DirectShow system doesn't necessarily know how to open Mp4 files (depending on what version of Windows you're running). DirectShow needs a source filter in order to recognize the MP4 container as a media file, a splitter to separate audio and video (and other) streams, and then decompression codecs to decompress the audio and video. So you may need to install DirectShow source filter for MP4, a splitter filter for Mp4, and codecs in order DirectShow to open MP4 files.

It can be hard to tell exactly what components are being used by DiretShow. What's used will depend on what filters you have installed and their priorities. Using GraphStudio to open your video shows the following graph on my computer:



The source filter (on the left) is Haali. That acts as both a source filter and splitter for MP4 files. The output of that filter is routed to ffdshow for video decoding and (via the DTV/DVD audio filter) ffdshow for audio decoding. Finally the decompressed video is sent to the graphics driver (Video Renderer) and the decompressed audio to the audio card (DirectSound Device). When opening the file in VirtualDub the decompressed audio and video are sent to VirtualDub rather than the output devices.

DirectShow should be the method of last resort for opening A/V files in VirtualDub. What you get will depend on what's installed on a particular system. And DirectShow isn't necessarily frame accurate. What frame you get may vary depending on whether you decode the video linearly or seek through it randomly. And since your video is variable frame rate, and VirtualDub only handles constant frame rate, there may be problems with that. In my case, Haali (I believe) is reporting the video as 25 fps because the video is VFR and it has to tell VirtualDub something.

[DogDay]

jagabo you are really helping me a lot. Now I understand why 3 icons are shown in my taskbar (haali, ffdshow audio and ffdshow video).

Now I know that some frames get lost (yes, I have learned how to install and make work the filter and how to open the video via ffmpegsource-avisynth and it reports 29,6 frames while opening it via DirectShow seems to be 25fps).

I have Installed Haali too. This is how the video looks like:



Only thing its strange for me is that I can open the video in Virtualdub via ffmpeg-source + avisynth. But cant open it in Media Player Classic the same way (with the same .avs script)

I learn a lot with your posts. Your help is really great apprecited. Thanks so much.

[jagabo]

Only thing its strange for me is that I can open the video in Virtualdub via ffmpeg-source + avisynth. But cant open it in Media Player Classic the same way (with the same .avs script)

64 bit vs. 32 bit issues? The 32 bit and 64 bit A/V systems are completely separate under 64 bit Windows. So a 32 bit player/editor requires that you have 32 bit AviSynth, codecs, and source filters. A 64 player/editor requires 64 bit AviSynth, codecs, and filters. Neither system can see the other system's components.

I learn a lot with your posts. Your help is really great apprecited. Thanks so much.

I'm glad it's helped you out.

[DogDay]

Nice you mentioned it: 64 bit vs. 32 bit issues. Dont know how but you have introduced me to another world. Now I have learned how to make things work in my home 64 bits computer.

I have learned how to choose the preferred filters to use (in W8 64 bits), I've learned how to make Avisynth work in a 64 bits environment, I begin understanding GraphStudio ... by the way: in your GraphStudio screenshot it seems you decode audio twice, first with MS DTV-DVD audio decoder and after that with ffdshow audio decoder dont you? Why?

I understand this is completly offopic, but Im very pleased learning from you.

[jagabo]

by the way: in your GraphStudio screenshot it seems you decode audio twice, first with MS DTV-DVD audio decoder and after that with ffdshow audio decoder dont you? Why?

MS DTV-DVD audio decoder inserted itself for custom channel mapping. It's possible to bypass that filter and route the AAC audio directly to the ffdshow.

[DogDay]

So ... perhaps its completly wrong but can I create an schema with GraphStudio to open a video file with some filters and save it to import it into Virtualdub? I have been trying but no way.

[jagabo]

can I create an schema with GraphStudio to open a video file with some filters and save it to import it into Virtualdub?

No, you can't do that. At least, I don't know of any way.

I would use AviSynth to do such things.