4:2:2, GOP, Broadcast safe audio

[joobny]

Hi all,

I'm creating a TV ad for broadcast in the USA. There are a few things on a spec sheet that I've received which I don't understand - I hope you can clear these up for me.

It says that HD video should be in 4:2:2 which I understand to be a colour space. If footage that I'm using wasn't shot in 4:2:2, how do I convert it so that it is? Is this something that I can do within After Effects or Premiere Pro?

For SD submissions it mentions having a 9 frame GOP. The HD specs say 'GOP structure not defined'. This is something I've never heard of. From Googling, I get that GOP stands for Group of Pictures, but I don't know how this is something that I can alter or adjust in After Effects or Premiere Pro?

Lastly, the spec sheet says that average digital audio levels should be between -16dBFS and -20dBFS with high peaks between -10dBFS and -12dBFS and a maximum of three peaks per second. I guess you could call this "broadcast safe audio". In After Effects or Premiere Pro, is there a technique for monitoring the audio to make sure it sticks within these boundaries? And what techniques do I use to adjust it if it's off?

Hope that's not too much of a ramble - any tips appreciated.

Many thanks,
Jonnie.

[smrpix]

Don't they mention video levels, colorspace, frame rate and delivery format? You need to know those before you can begin to deal with GOP or 4:2:2.

You monitor your audio by playing it, listening to it, watching your meters and adjusting the levels if they're too high (or low.) At the end you can apply a hard limiter in Premiere, Audition or AE. (Though, I wouldn't use after effects for audio.)

[joobny]

Hi smrpix,

Thanks for the reply.

They do mention video levels, frame rate and delivery format, but I think I understand how I need to deal with those.

Maximum setup levels are 7.5 IRE (SD) and ITU-R BT.79 compliant (HD).
Maximum luminance levels are 100 IRE (SD) and ITU-R BT.79 compliant (HD).
Maximum chroma levels are 120 IRE (SD) and ITU-R BT.79 compliant (HD).

To deal with that in After Effects I was going to create an adjustment layer with the Broadcast Colors and Levels (white output to 235 and the black output to 16) effects applied to it.

Frame rate will be 29.976i and delivery format (for HD) can be H.264, 50MB/s, 1920x1080.

I think that's all stuff that I can handle (though we'll soon find out!), but I've never dealt with GOP or 4:2:2 before. I'm going to be using stock footage so it's likely that it will have been filmed with a variety of different cameras and come in various different formats.

Thanks again.

[poisondeathray]

Frame rate will be 29.976i and delivery format (for HD) can be H.264, 50MB/s, 1920x1080.

h.264 at 50Mb/s 4:2:2? You sure about that?

Preferred broadcast submission format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder.

Long GOP h.264 4:2:2 is not a commonly used format at 50Mb/s . For h.264, more typical is AVC-Intra 4:2:2 at 100Mb/s

[joobny]

Frame rate will be 29.976i and delivery format (for HD) can be H.264, 50MB/s, 1920x1080.

h.264 at 50Mb/s 4:2:2? You sure about that?

Preferred broadcast delivery format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard deliverable format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder.

Long GOP h.264 4:2:2 is not a commonly used format at 50Mb/s . For h.264, more typical is AVC-Intra 4:2:2 at 100Mb/s

Yeah I have the spec sheet sitting right here. For HD it says GOP structure not defined.

Are 4:2:2 and GOP simply things that are left to the export stage of a project then?

Thanks for the reply!

[smrpix]

Yeah, I expected your answer would come back looking like what poisondeathray is saying.

"Preferred broadcast submission format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder."

And you're already doing what I would have advised here:

"To deal with that in After Effects I was going to create an adjustment layer with the Broadcast Colors and Levels (white output to 235 and the black output to 16) effects applied to it."

REVISED!: You can customize the h.264 legacy preset in AME. Set your profile to High, 5.1, and your target and maximum bitrate levels to 50. You're forced to use AAC Audio. This still only gives you 4:2:0.

You may want to send them a 50mb XDCAM as well, since it's so common.

GOP and colorspace are often (usually?) defined by the delivery format. That's why I couldn't give you a straight answer initially.

[Cornucopia]

And, BTW if you didn't already know this: XDCAM when in HD mode uses MPEG2 encoding, not DV, not MPEG4, not AVC/H.264. XDCam has been around since 2003. You can look this up...

Probably SHORT GOP also (I-frame distance = ~6-12). 4:2:2 is color subsampling format, not colorspace (Colorspace is YUV ITU BT.709 (not 79) - IOW, standard digital HD). Also, framerate is 29.97i, not 29.976i. You are getting that confused with 23.976 (which is pulled-down 24p).

For audio, neither AE nor PPro are true audio editors - they have some tools, but not enough. If you have those apps, don't you have Audition? v3.0 is a good one. It will give you both PEAK and RMS levels and other stats, and you can apply either dynamic range compression or peak limiting (or both), as well as Normalization (last resort, an all to be done with dither) to massage the signal into compliance.

Scott

[[_chef_]]

Frame rate will be 29.976i and delivery format (for HD) can be H.264, 50MB/s, 1920x1080.

h.264 at 50Mb/s 4:2:2? You sure about that?

Preferred broadcast submission format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder.

Long GOP h.264 4:2:2 is not a commonly used format at 50Mb/s . For h.264, more typical is AVC-Intra 4:2:2 at 100Mb/s

Industry standard and most used "standard" for broadcasting submissions aka FEEDS.
And not only in the USA and UK, of course in whole europe and beyond too!

Ask a Feedhunter or satfreak, they will tell you something about 4.2.2.

[joobny]

Thanks for all the replies. I have a much greater understanding of 4:2:2 and YUV now, thanks to this article that a member on Creative Cow showed me:

http://blogs.adobe.com/VideoRoad/2010/06/color_subsampling_or_what_is_4.html

Yeah, I expected your answer would come back looking like what poisondeathray is saying.

"Preferred broadcast submission format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder."

And you're already doing what I would have advised here:

"To deal with that in After Effects I was going to create an adjustment layer with the Broadcast Colors and Levels (white output to 235 and the black output to 16) effects applied to it."

REVISED!: You can customize the h.264 legacy preset in AME. Set your profile to High, 5.1, and your target and maximum bitrate levels to 50. You're forced to use AAC Audio. This still only gives you 4:2:0.

You may want to send them a 50mb XDCAM as well, since it's so common.

GOP and colorspace are often (usually?) defined by the delivery format. That's why I couldn't give you a straight answer initially.

It seems there isn't any point in converting 4:2:0 to 4:2:2 because the footage won't gain anything - so do I just have to avoid using 4:2:0 footage if broadcasters don't like it? I don't see why I'd want to, but if I was to convert footage from 4:2:0 to 4:2:2, would I just need to transcode it using the AME preset you mentioned?

And, BTW if you didn't already know this: XDCAM when in HD mode uses MPEG2 encoding, not DV, not MPEG4, not AVC/H.264. XDCam has been around since 2003. You can look this up...

Probably SHORT GOP also (I-frame distance = ~6-12). 4:2:2 is color subsampling format, not colorspace (Colorspace is YUV ITU BT.709 (not 79) - IOW, standard digital HD). Also, framerate is 29.97i, not 29.976i. You are getting that confused with 23.976 (which is pulled-down 24p).

For audio, neither AE nor PPro are true audio editors - they have some tools, but not enough. If you have those apps, don't you have Audition? v3.0 is a good one. It will give you both PEAK and RMS levels and other stats, and you can apply either dynamic range compression or peak limiting (or both), as well as Normalization (last resort, an all to be done with dither) to massage the signal into compliance.

Scott

The term GOP still confuses me as it's not something that I've ever come across before now. I'm unsure of how it's adjusted or altered to suit a broadcasters specs?

Thanks for pointing out my errors. Am I correct in thinking that you'd want to pull down 24p to 23.976 so that it could then be pulled down to 29.97?

I hadn't realised before, but you're right - I do have Audition, so I'll do a bit of swatting on it to see how I can control my audio the best I can.

Frame rate will be 29.976i and delivery format (for HD) can be H.264, 50MB/s, 1920x1080.

h.264 at 50Mb/s 4:2:2? You sure about that?

Preferred broadcast submission format is usually XDCAM-HD ie. 50Mb/s mpeg2 4:2:2. This is an industry standard format for USA, and UK (BBC). There will be a preset for "XDCAMHD 4:2:2" in Adobe Media Encoder.

Long GOP h.264 4:2:2 is not a commonly used format at 50Mb/s . For h.264, more typical is AVC-Intra 4:2:2 at 100Mb/s

Industry standard and most used "standard" for broadcasting submissions aka FEEDS.
And not only in the USA and UK, of course in whole europe and beyond too!

Ask a Feedhunter or satfreak, they will tell you something about 4.2.2.

I'm going to have to do a bit of reading on XDCAMHD now as well - thanks!

Cheers again for all the replies. Really appreciate it.

Jonnie.

[poisondeathray]

It seems there isn't any point in converting 4:2:0 to 4:2:2 because the footage won't gain anything - so do I just have to avoid using 4:2:0 footage if broadcasters don't like it? I don't see why I'd want to, but if I was to convert footage from 4:2:0 to 4:2:2, would I just need to transcode it using the AME preset you mentioned?

Yes, normally there wouldn't be any point. But many places will reject it otherwise. There are 2 different things usually discussed here: acquisition requirements vs. submission requirements. Many require acquisition (ie. what the native camera footage records in ) to be in 50Mb/s 4:2:2 as a minimum as well as submission (what you give them after editing, color correction etc...).

If you use that XDCAM preset , yes it will meet their submission requirements, but if source footage was 4:2:0, it might not meet their acquisition requirements - You have to check with whoever is receiving it or look more closely at the guideline sheet . Some places are very picky as to what they will accept or reject. The bottom line is you should give them what they want.

The term GOP still confuses me as it's not something that I've ever come across before now. I'm unsure of how it's adjusted or altered to suit a broadcasters specs?

GOP is simply group of pictures
http://en.wikipedia.org/wiki/Group_of_pictures

In short - It's a form of temporal compression where some frames do no contain all the information from the current frame. They code and store differences between frames. I frames are complete and inclusive, P and B are not . The max GOP length is the max I to I interval . Most broadcasters want a set GOP length, not adaptive GOP length (The XDCAM preset will be CBR and have set gop length)

You can adjust these settings in some programs, not in others. XDCAM-HD is very standardized, so usually nothing needs to be adjusted (it's already adjusted "behind the scenes" for you if you switch between formats and framerates)

Am I correct in thinking that you'd want to pull down 24p to 23.976 so that it could then be pulled down to 29.97?

Yes, 24.0 footage is slowed to 23.976 and has 3:2 pulldown applied . Unless you are using film , most cameras will be shooting 23.976 in the first place

Some places will accept 23.976p native footage (no pulldown), but the safest is usually 23.976p with 3:2 pulldown (59.94i) for broadcast folks

[aedipuss]

there are lots of places that are very picky about the videocams used, like the bbc that won't accept main footage from a cmos sensor cam even if it were 4:2:2 and met all the other requirements.

[poisondeathray]

there are lots of places that are very picky about the videocams used, like the bbc that won't accept main footage from a cmos sensor cam even if it were 4:2:2 and met all the other requirements.

Yes, BBC is very strict. But the "CMOS" part isn't true. There are some CMOS cameras on their approved HD list for main programming (not just independent programs) e.g. XF300/305 . EX1R/3 are allowed with external recorder (they don't meet the bitrate requirements natively)

[aedipuss]

there are lots of places that are very picky about the videocams used, like the bbc that won't accept main footage from a cmos sensor cam even if it were 4:2:2 and met all the other requirements.

Yes, BBC is very strict. But the "CMOS" part isn't true. There are some CMOS cameras on their approved HD list for main programming (not just independent programs) e.g. XF300/305 . EX1R/3 are allowed with external recorder (they don't meet the bitrate requirements natively)

hard to keep up with their rules, a few months ago it was NONE ALLOWED

[joobny]

If you use that XDCAM preset , yes it will meet their submission requirements, but if source footage was 4:2:0, it might not meet their acquisition requirements - You have to check with whoever is receiving it or look more closely at the guideline sheet . Some places are very picky as to what they will accept or reject. The bottom line is you should give them what they want.

The term GOP still confuses me as it's not something that I've ever come across before now. I'm unsure of how it's adjusted or altered to suit a broadcasters specs?

GOP is simply group of pictures
http://en.wikipedia.org/wiki/Group_of_pictures

In short - It's a form of temporal compression where some frames do no contain all the information from the current frame. They code and store differences between frames. I frames are complete and inclusive, P and B are not . The max GOP length is the max I to I interval . Most broadcasters want a set GOP length, not adaptive GOP length (The XDCAM preset will be CBR and have set gop length)

You can adjust these settings in some programs, not in others. XDCAM-HD is very standardized, so usually nothing needs to be adjusted (it's already adjusted "behind the scenes" for you if you switch between formats and framerates)

Am I correct in thinking that you'd want to pull down 24p to 23.976 so that it could then be pulled down to 29.97?

Yes, 24.0 footage is slowed to 23.976 and has 3:2 pulldown applied . Unless you are using film , most cameras will be shooting 23.976 in the first place

Some places will accept 23.976p native footage (no pulldown), but the safest is usually 23.976p with 3:2 pulldown (59.94i) for broadcast folks

Thanks again for the replies.

I've been playing around with Adobe Media Encoder (CS6) but I haven't been able to find a XDCAM preset. Is there somewhere that I can download it from?

It also seems that Adobe Media Encoder doesn't give you many options in terms of defining a GOP structure. The only time I've ever seen it is when choosing the MPEG-2 format and it refers to M and N frames. My spec sheet refers to 9 frame GOP with MPEG-2 (to get this it looks like I'd have to set M to 3 and N to 9) and "GOP structure not defined" with H.264 - I'm assuming that's because you can't alter GOP settings with H.264, because it handles them differently from MPEG-2 and it only has one setting?

Again with 4:2:2. In AME the MPEG-2 format allows me to choose 4:2:2 from the "profile" drop-down, but H.264 only has Baseline, Main or High as options.

From reading another post online it seems that a program like Telestream Episode would be better for this job?

I've attached the delivery spec sheet that I've been given from DG for you to have a look at if you like.

Thanks again,
Jonnie.

[poisondeathray]

I've been playing around with Adobe Media Encoder (CS6) but I haven't been able to find a XDCAM preset. Is there somewhere that I can download it from?

It should be included , I recall reading somewhere there were some elements missing from the "cloud" version of Adobe Suite, but I think they have that patched - just do an update

It also seems that Adobe Media Encoder doesn't give you many options in terms of defining a GOP structure. The only time I've ever seen it is when choosing the MPEG-2 format and it refers to M and N frames. My spec sheet refers to 9 frame GOP with MPEG-2 and "GOP structure not defined" with H.264 - I'm assuming that's because you can't alter GOP settings with H.264, because it handles them differently from MPEG-2?

M and N define the GOP structure. N is the number of frames in a GOP, M is the number of b-frames in a GOP .

Again with 4:2:2. In AME the MPEG-2 format allows me to choose 4:2:2 from the "profile" drop-down, but H.264 only has Baseline, Main or High as options.

From reading another post online it seems that a program like Telestream Episode would be better for this job?

h.264 as 4:2:2 can only be done by using AVC-Intra preset in AME . There is no GOP length option in AVC-Intra (intra means GOP size of 1)

But as mentioned above, the licensed encoders included are "watered down" versions and don't give you access to all the options. Telestream Episode, or Rovi Totalcode (formerly Mainconcept) will give you more access to encoding options. Open source, free encoders give you access to even more options


From the spec sheet, these guys are obviously MAC based. They prefer prores for their HD submissions

Now the spec sheet is a bit bizzare, SD video specs are fairly standard, but they want 18Mb/s , that standard used is typically IMX50 (50Mb/s) . The audio request is bizzare as well, usually uncompressed audio is used, not MP2

I would give them prores HQ for HD submissions (since that is their preferred format). The problem is you can't encode to prores on a PC, unless you use open source solutions like ffmpeg . ffmpeg's implementation isn't "apple certified", but works. The thing is you don't want to take any chances with this sort of thing

[joobny]

Thanks again mate, appreciate all your input. I think I get GOP now after some serious head scratching...

It is the cloud version of CS6 that I'm using so I updated it.

I think the way AME is laid out is getting me confused between containers, codecs and formats. For instance, I understand H.264 to be a codec but it's listed in the Format options. And when I pick QuickTime from the Format options I can choose H.264 as a codec.

Similarly I can only find the XDCAM-HD codec under the MXF OP1a format. In the video settings for that format you can choose the codec to be "XDCAMHD 50 NTSC 4:2:2" or "AVC-Intra Class 50 1080". The problem with this is that it'll spit out a .mxf file and that spec sheet requires a .mov. Would I get away with simply changing the extension of the video file? Or is it going to be a case of using a different encoder to use encode these into a .mov container?

I'd like to download the trial of Episode but I don't want it to run out before I have to deliver this project... Can you recommend any free open source encoders?

h.264 as 4:2:2 can only be done by using AVC-Intra preset in AME . There is no GOP length option in AVC-Intra (intra means GOP size of 1)

If I choose MXF OP1a then and use the AVC-Intra codec, does that mean I'd meet that spec sheet's requirement of "H.264 (.mov)" for HD delivery if I change the file extension from .mxf to .mov?

I'm going to install the ProRes codecs for QuickTime and see if I can have a play with meeting their ProRes requirements too.

Sorry for so many questions - you've all been a great help in getting my head around this. Thanks again.

[poisondeathray]

I think the way AME is laid out is getting me confused between containers, codecs and formats. For instance, I understand H.264 to be a codec but it's listed in the Format options. And when I pick QuickTime from the Format options I can choose H.264 as a codec.

Anything "MOV" wrapped needs to be accessed through quicktime. The problem is not all options are available on a PC . If you want to follow their recommendations exactly you need a Mac. You can use open source implementations (and they work, import in Mac software correctly, but aren't "Apple certified"). Most places will accept XDCAM-HD , although they might want it MOV wrapped (It can come as MP4, MXF, or MOV)

Similarly I can only find the XDCAM-HD codec under the MXF OP1a format. In the video settings for that format you can choose the codec to be "XDCAMHD 50 NTSC 4:2:2" or "AVC-Intra Class 50 1080". The problem with this is that it'll spit out a .mxf file and that spec sheet requires a .mov. Would I get away with simply changing the extension of the video file? Or is it going to be a case of using a different encoder to use encode these into a .mov container?

If I choose MXF OP1a then and use the AVC-Intra codec, does that mean I'd meet that spec sheet's requirement of "H.264 (.mov)" for HD delivery if I change the file extension from .mxf to .mov?

No, these are completely different containers. You cannot just change the extension. You can re-wrap the XDCAM-HD into MOV with various tools, but not the AVC-I 100. (You don't want to submit AVC-I 50)

I'd like to download the trial of Episode but I don't want it to run out before I have to deliver this project... Can you recommend any free open source encoders?

The free ones commonly used to encode to prores are ffmbc and ffmpeg. ffmbc is sort of the broadcast oriented version of ffmpeg. These are command line utilities, although there are some GUIs for them

I'm going to install the ProRes codecs for QuickTime and see if I can have a play with meeting their ProRes requirements too.

The windows ProRes codecs for QT come with QT install now , it's not a separate installer anymore. You cannot encode ProRes on a PC with QT (only though open source ffmpeg/ffmbc, but they aren't "Apple Certified") . I haven't had problems importing the ffmbc version of prores on a Mac, but some people might not want to take that chance.

Also, the windows version of QT Pro cannot encode 4:2:2 h.264, only the 4:2:0 variant - you need a Mac for that

You can use x264 to encode 4:2:2, but x264 sometimes causes some problems when wrapped in MOV container


As you can see, in this day and age, PC/MAC still give headaches !!

If I was doing this, I would ask if the will accept XDCAM-HD / MOV. If no, I would submit Prores
http://code.google.com/p/ffmbc/wiki/XDCAMHD422Encoding
http://code.google.com/p/ffmbc/wiki/ProResEncoding

[joobny]

Anything "MOV" wrapped needs to be accessed through quicktime. The problem is not all options are available on a PC . If you want to follow their recommendations exactly you need a Mac. You can use open source implementations (and they work, import in Mac software correctly, but aren't "Apple certified"). Most places will accept XDCAM-HD , although they might want it MOV wrapped (It can come as MP4, MXF, or MOV)

No, these are completely different containers. You cannot just change the extension. You can re-wrap the XDCAM-HD into MOV with various tools, but not the AVC-I 100. (You don't want to submit AVC-I 50)

Sorry, I should have mentioned in the beginning that I'm actually using a Mac. When I was originally posting I couldn't get XDCAM to appear as a codec under any format apart from MXF OP1a. However I was investigating ProRes codecs and installed these:

http://support.apple.com/kb/DL1396

Now I can see the various XDCAM and ProRes codecs under the QuickTime format option - thanks for clearing up my misunderstanding.

You can use x264 to encode 4:2:2, but x264 sometimes causes some problems when wrapped in MOV container

As you can see, in this day and age, PC/MAC still give headaches !!

If I was doing this, I would ask if the will accept XDCAM-HD / MOV. If no, I would submit Prores
http://code.google.com/p/ffmbc/wiki/XDCAMHD422Encoding
http://code.google.com/p/ffmbc/wiki/ProResEncoding

Thanks a lot for all your pointers - this has given me a much better grasp of the export process than I had before. I normally export for YouTube or Vimeo which is a much more straightforward task...

REVISED!: You can customize the h.264 legacy preset in AME. Set your profile to High, 5.1, and your target and maximum bitrate levels to 50. You're forced to use AAC Audio. This still only gives you 4:2:0.

Had a play with this earlier. Just wondering how you can tell if it's 4:2:0 or 4:2:2 in AME? I don't see it showing up anywhere when I change all the settings. The only time I've ever actually seen something say 4:2:2 is in the name of some of the ProRes/XDCAM codecs and in the MPEG-2 format's profile options.

Thanks again.