MFX details and compatibility; what about ffmpeg?

[Tuomas Sebastien]

Now that I finaly can convert 720p clips with updated clip browser to MFXs do I loose something in conversion? How about 1080p clips? Are MFXs forced from 1920x1080 MP4 native to 1440x1080 like other XDCAM files are?

I tried loading MFX to Avid, it loads but it doesn't work when played. Premiere CS3 starts the import but then stops as it doesn't recognize the file format. Is Vegas pro the only application that actually understands the converted MFXs? If so does this mean that if I don't buy prospectHD there's no way to edit HQ clips on PC except on Vegas or by first converting MP4 to MFX and then rendering it to something else on Vegas that can be recognized by adobe or avid?

Does anyone know what ffmpeg actually is? Since it is used to show the MP4 clips on clip browser can it somehow be used with adobe or avid? There's no ready made installer for it so does it need to be compiled and installed manually? I found converter, that someone had programmed from ffmpeg, which converts MP4s to DNxHD quicktime that avid can understand but it only works with 1080p, not 720p. (and i haven't tested this converter yet but the fact that there is one prooves that ffmpeg can somehow be used to make MP4s from EX1 understandable file)

It is starting to look like that buying EX1 this early is a nightmare rather than dream come true.

[Andreas Johansson]

http://ffmpeg.mplayerhq.hu/


Or just search the forum I have posted several times about ffmpeg and Avid.

[Paul Newman]

Try Edius Broadcast, works happily with MXF, I get realtime without any problems straight out to my HD monitor, full spec 1920x1080. The next release for Edius is at the end of January or beginning of Feb and will have an EX1 direct import application added to make the clip "unwrap" thingy outmoded. I even get playback off my Rev Pro archive discs at 1920x1080 - very cool indeed.

Paul

[Vincent Mesman]

Originally Posted by Tuomas Sebastien

Now that I finaly can convert 720p clips with updated clip browser to MFXs do I loose something in conversion? How about 1080p clips? Are MFXs forced from 1920x1080 MP4 native to 1440x1080 like other XDCAM files are?

The Sony software is re-wrapping the mp4 data to mxf without transcoding.
Since FFMPEG is able to decode the mp4 file to a non-long-GOP format that all video editors can read, there is no need to rewrap to mxf.

[Tuomas Sebastien]

Originally Posted by Vincent Mesman

The Sony software is re-wrapping the mp4 data to mxf without transcoding.

Does this mean that the quality drops? Or what does it mean when it re-wrapped without transcoding?

Originally Posted by Vincent Mesman

Since FFMPEG is able to decode the mp4 file to a non-long-GOP format that all video editors can read, there is no need to rewrap to mxf.

After looking around Andreas' posts I found executable ffmpeg and made lots of test with different video and audio codecs. I found following command line to work:
ffmpeg -i input.mp4 -vcodec dnxhd -b 60Mb -acodec copy output.mov
The file imported in adobe perfectly and audio was also there.

Now, since I'm not sure how dnxhd 60Mb compares to 35Mbps HQ MP4, could someone please explain me how I should do the conversion without loosing quality? In what format I should convert my MP4s and what switches should I use with the ffmpeg to do this? I have bookmarked the ffmpeg help site but I'm overhelmed by all the different codecs, bitrates and color samples that it offers on selectable switches. Can I upsample to 4:2:2 too while converting? How about bith depth? Some good command line examples for setups that have been found good and working would be greatly appreciated.

[Andreas Johansson]

Originally Posted by Tuomas Sebastien

I found following command line to work:
ffmpeg -i input.mp4 -vcodec dnxhd -b 60Mb -acodec copy output.mov

Thats great news beacause that would tell me your using a 720p clip since 60Mbit is a 720p bitrate.

This is a good ffmpeg for pro users help site:

http://www.itbroadcastanddigitalcine...peg_howto.html

This is the command line I got from Baptiste who is developing the DNxHD stuff in ffmpeg.

Progressive:
fmpeg -i inputfile.mp4 -vcodec dnxhd -b 185Mb -acodec pcm_s16le outputfile.mov

Interlaced: (The difference is the -flags +ildct)
ffmpeg -i inputfile.mp4 -vcodec dnxhd -b 185Mb -flags +ildct -acodec pcm_s16le outputfile.mov

And this is a link to a DNxHD white paper:
http://www.avid.com/resources/whitepapers/DNxHD_WP3.pdf

We are thinking of using 36Mbit DNxHD but all people we talk to say to use 185Mbit or maybe 120Mbit and that 36Mbit is for offline.

But since 36Mbit is higher than the original 35Mbit it would probably still look good enough for us and since we are a school and have lots of raw material going to be put on servers we need to keep the filesize low for now. We are using the same server for this as we did when using DV 25Mbit so we are going to run short on space faster now.

But if you don't have a problem using allot of GB on disc then go for Max Mbit for the specific resolution and framerate you use.

1080p/25 DNxHD 185 1920 x 1080 8bit 25fps = -b 185Mb
720p/50 DNxHD 175 1280 x 720 8bit 50fps = -b 90Mb
1080i/50 DNxHD 185 1920 x 1080 8bit 25fps = -b 185Mb

More settings for other framerates:
http://www.itbroadcastanddigitalcine...#Encoding_VC-3

[Perrone Ford]

I realize this is an older thread, but I am hoping someone has an answer.

Has anyone cracked the nut of getting ffmpeg to transcode the Sony .MXF format to DNxHD? This would be the holy grail for what I am trying to do. ffmpeg crashes every time I try it. And none of the media encoders seem to be able to do this either.

Thanks.

[David C. Williams]

VLC can play MXF and VC-3, and has transcode functions. I haven't tried it though?

[Bill Ravens]

Perrone...

Not exactly sure what your issue's are with this x-code. I can do it routinely in avid. Even vegas works most of the time. Tmpgenc 4 and procoder will also do the xcode. Pretty sure squeeze 5 does it as well.

[Tuomas Sebastien]

Currently using ffmpeg is hardly necessary since the EX's MP4-format has now been adopted by all the major NLE systems.

But if you still have some problems, I'd suggest that you try using the ffmpeg to original MP4 file to encode it to DNxHD instead of trying to re-encode from already encoded MFX which you got by using the clip browser.

[Alister Chapman]

The MXF's that I've created via the clip browser have all worked in AVid Media Composer v3 for me.

[Tom Roper]

No one has mentioned the free Snell and Wilcox utility MXFDesktop for unwrapping the mxf container to mpeg-2.

[Perrone Ford]

Originally Posted by Bill Ravens

Perrone...

Not exactly sure what your issue's are with this x-code. I can do it routinely in avid. Even vegas works most of the time. Tmpgenc 4 and procoder will also do the xcode. Pretty sure squeeze 5 does it as well.

I'm not using Avid, or I suspect this would be a non-issue. And I can do the transcode easily in Vegas. I was hoping to have a simple way to do a batch recode of Sony MXF files to DNxHD .MOV files OUTSIDE the editor so I could simply farm them off to an idle workstation.

[Perrone Ford]

Originally Posted by Tuomas Sebastien

Currently using ffmpeg is hardly necessary since the EX's MP4-format has now been adopted by all the major NLE systems.

But if you still have some problems, I'd suggest that you try using the ffmpeg to original MP4 file to encode it to DNxHD instead of trying to re-encode from already encoded MFX which you got by using the clip browser.

apparently, you use a Mac. On a PC, the clip browser software re-wraps to an MXF and not a .mov file like it does on the Mac. Which means I have to play the game of trying to make the conversion.

By the way, the EX1 produces Mpeg2 files, not Mpeg4. In either case, I'd prefer not to use any interframe codec in my NLE if possible which is why I was hoping to transcode to a file using my codec of choice.

[Perrone Ford]

Originally Posted by Tuomas Sebastien

But if you still have some problems, I'd suggest that you try using the ffmpeg to original MP4 file to encode it to DNxHD instead of trying to re-encode from already encoded MFX which you got by using the clip browser.

I finally figured this out. The .mp4 files are located in the menu structure in the card's BPAV file structure on the media card. Not sure how this works on Macs.

Apparently, ffmpeg is able to access and convert these raw files into DnxHD coded .mov files. You were right, the answer just wasn't obvious. At least not to me.

It appears that I can now extract all the .mp4 files from my cards into a temporary folder for my project, and have my utility batch convert these for me to DNxHD 36 and 175 outside the NLE overnight. Then I can move the resulting files to their permanent homes in the morning and begin my editing.

Pretty simply workflow, and it's going to be quite efficient I think.

Thank you all very much!