Guides

GSpot

We'll be using GSpot to analyze the video and audio in our source files. If you're not familiar with it, you can read our guide to using GSpot for basic instructions on opening files for analysis.

ffdshow and the Haali Media Splitter

By using ffdshow and the Haali Media Splitter, you should be able to open (play) all of our source files. Our guide for playing MP4 files includes instructions for installing ffdshow and Haali. If you don't have an MPEG-2 decoder installed, like from a software DVD player, you can also use ffdshow to play MPEG files. Once you have it installed, the ffdshow program group on the start menu will have an option called Video Decoder Configuration. The Video Decoder Configuration window has a list of formats it will decode. By default MPEG2 is disabled. From the dropdown list in the field to the right, select libavcodec. Click the Okay button and you should be able to read MPEG-2 files. You should also have XviD set to libavcodec.

First Impressions

With our list of requirements for DVD compliance in mind, the first thing we know by just looking at our files is that some of them can't possibly meet all of them. In particular, The Arctic Giant is in an M4V container, while Jungle Drums, The Mad Scientist, Terror On The Midway, The Underground World, and Volcano are all in MP4 containers. This indicates they're encoded in some MPEG-4 format. Most likely neither the video or audio in these files will make a legal DVD asset without some encoding. Without further analysis we won't be able to tell any specifics about the MPEG files.

Using GSpot

GSpot has a lot of information, including pretty much everything we need to find out right now. Following the instructions in the GSpot guide, open the file you downloaded called arctic_giant.m4v. Depending on your Windows settings you may not see the .m4v at the end. GSpot should show you the following video information. The codec is AVC1, which means it uses MPEG-4 H.264 (AVC) encoding.

The length in frames and time is listed in the middle, as is the bitrate. There's no magic formula to convert AVC bitrate to MPEG-2 bitrate so we won't need to worry about it. Notice that Pics/s (Pictures per second) and Frames/s (Frames per second) have numbers, indicating progressive video at 29.97fps.

Resolution is 640x480, which isn't legal for DVD, however the aspect ratio is 1.33, indicating full frame film. This is fine for a DVD asset.

Rendering

Since GSpot can't get all the information possible without further analysis, we need to have it attempt to render (play) it. At the bottom of GSpot is the Proposed Codec Solutions and Tests area. On the left are two columns of buttons grouped together and a third column by itself. Start by clicking the top blue button in the column under Vid. You'll get a message that GSpot can't render the video type. Click the top blue button under MS A/V. This will tell GSpot to have Windows render the file. ffdshow should be listed for reading both the video and audio streams.

Audio

The audio is in AAC (Advanced Audio Coding) format, which is similar to MP3, only more compressed. Fortunately ffdshow can read this. Unfortunately it's sampled at 44,100Hz, while DVD-Video requires 48,000Hz.

Moving on to the MP4 files, opening each of them will reveal files encoded as XviD, a different MPEG-4 compression standard than AVC. They have lower resolutions - still not DVD compliant, and framerates of 23.976fps. That's the framerate used with 2:3 pulldown to create a telecine effect with digital video. Not legal for a DVD asset, but ready for re-encoding. Aspect ratio is off slightly, and actually comes closer to full frame film's 1.37:1 than television's 1.33:1. Finally, the audio is AAC again, but this time it's mono instead of stereo.

MPEG Files

Opening our MPEG-2 files will be much more productive in terms of information available. GSpot knows more about this particular container and will give you a lot of information and suggestions. Let's start by opening Destruction Inc. Another section in the middle of the Video area is lit up. The important information is where it says 15 max. That tells us we have a GOP size of 15.

Bitrate is listed as 6,482. Below that I/L is lit up in green, indicating interlaced video. The number next to Fields/s confirms this, showing an NTSC fieldrate. NTSC and BFF, which stands for Bottom Field First, are also lit up. The video is considered an NTSC (Full D1) video stream.

The resolution, being correct for NTSC television, is also DVD compliant. The AR is a somewhat strange 1.5:1.

Audio

The audio is MPEG-1 Layer-2, meaning MPA.

Extras

The MPEG-2 encoded extras are all NTSC video. Since the original sources are all film with a framerate of 24fps we know that they have 'hard pulldown' applied. That means if we need to re-encode it would be best to IVTC to recover the original progressive frames. We can't tell the maximum bitrate for sure, but it appears to be within DVD-V specs for every file. It's possible one or more trailer exceeds the limit of 9,800kbps, but given their relative high bitrates it's likely that we'll want to re-encode anyway so it shouldn't be a problem.

Audio Streams

Some of the extras have 2 channel AC-3 audio, which is fine for both PAL and NTSC. Others have MPEG audio, which will probably work for both NTSC and PAL, but is technically only an optional audio format for NTSC. This means that NTSC players aren't required to play it back. If you're picky about your audio it may be worth transcoding no matter what since MPA decoding in DVD players doesn't always work correctly. I'll give instructions for encoding everything to AC-3.

Time

The play time and number of frames are listed. I'm keeping track of time in seconds because it's the easiest way to combine them later for planning bitrate allocation.

Cartoons

The Arctic Giant

Time (in seconds): 512
AR: 1.33
Resolution: 640x480
Framerate: 29.97fps
Audio: AAC 2 Channel

Destruction Inc.

Time (in seconds): 500
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 6,482kpbs
GOP Length: 15
Audio: MPA

Electric Earthquake

Time (in seconds): 522
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 2,838kpbs
GOP Length: 15
Audio: AC-3 2 Channel

Eleventh Hour

Time (in seconds): 479
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 2,238
GOP Length: 15
Audio: AC-3 2 Channel

Jungle Drums

Time (in seconds): 468
AR: 1.36
Resolution: 480x352
Framerate: 23.976fps
Audio: AAC mono

The Mad Scientist

Time (in seconds): 481
AR: 1.36
Resolution: 480x352
Framerate: 23.976fps
Audio: AAC mono

The Mechanical Monsters

Time (in seconds): 615
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 2,757kbps
GOP Length: 15
Audio: AC-3 2 Channel

The Mummy Strikes

Time (in seconds): 394
AR: 1.33
Resolution: 720x480
Frame Type: Hybrid (Progressive & Interlaced)
Framerate: 29.97fps
Avg Bitrate: 6,906kbps
GOP Length: 15
Audio: MPA

Secret Agent

Time (in seconds): 448
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 6,457kbps
GOP Length: 15
Audio: MPA

Superman

Time (in seconds): 621
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 6,493kbps
GOP Length: 15
Audio: MPA

Terror On The Midway

Time (in seconds): 481
AR: 1.36
Resolution: 480x352
Framerate: 23.976fps
Audio: AAC mono

The Underground World

Time (in seconds): 476
AR: 1.36
Resolution: 480x352
Framerate: 23.976fps
Audio: AAC mono

Volcano

Time (in seconds): 464
AR: 1.36
Resolution: 480x352
Framerate: 23.976fps
Audio: AAC mono

Trailers

The 5000 Fingers of Dr T

Time (in seconds): 125
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 9,501kbps
GOP Length: 15
Audio: MPA

The Amazing Transparent Man

Time (in seconds): 97
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 9,498kbps
GOP Length: 15
Audio: MPA

Attack of the 50 Foot Woman

Time (in seconds): 106
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 9,499kbps
GOP Length:
Audio: MPA

The Deadly Mantis

Time (in seconds): 122
AR: 1.33
Resolution: 720x480
Frame Type: Interlaced
Framerate: 29.97fps
Avg Bitrate: 9,499kbps
GOP Length:
Audio: MPA

Main Feature

Our MPEG-2 encoded main feature poses an interesting problem because unlike the rest of our video it appears to have been encoded from a PAL source. The framerate is sped up by approximately 4% (from the original film), causing the audio to be shortened by the same amount. Both movies appear to have resolutions intended for computer playback as they don't match any standalone player format. Since both will need to be re-encoded to correctly match the television system the DVD is authored for, we only need the bitrate for a possible guideline when we're encoding to MPEG-2.

The 39 Steps

Time (in seconds): 4988
AR: 1.33
Resolution: 640x480
Frame Type: Progressive
Framerate: 25fps
Avg Bitrate: 2,009kbps
GOP Length: 12
Audio: MPA

Table of Contents

1. Introduction
2. Requirements for DVD Compliance
3. Analysis
4. Interpreting The Results