BestVideoMaker

Tsunami (TMPG) MPEG-2 encoder settings

If you want to release your video on DVD you will have to encode it in the MPEG-2 format first. MPEG-2 is the DVD video standard. You can take your DV tape to a post-production house and they will encode it for you; this generally results in high-quality MPEG-2 video, but it is inconvenient and does not make you independent.

The other option is to export your project as high-quality AVI file and convert it to an MPEG-2 video file using a software encoder. TMPGEnc (aka Tsunami encoder) is one of the best software encoders around and I have used it with great success to encode videos in the MPEG-2 format for DVD-authoring purposes. The Tsunami encoder is very reasonably priced and all in all it is an excellent choice for filmmakers who want to encode their videos in high-quality MPEG-2 affordably and without having to rely on third-party services. This article describes the recommended settings for the production of high-quality MPEG-2 video expressly aimed at DVD production.

TMPG encoder main window

Open the Tsunami encoder. Under Stream type, select ES (Video only).

Now click on Setting. You will see six tabs: video, advanced, GOP structure, quantize matrix, audio and system. The ones you have to worry about are the first four.

Video

Screen type: choose MPEG-2. This is the DVD video standard.

Size: if you're encoding MPEG-2 video to be distributed on DVDs there are only two possible sizes you can use: 720 x 480 for NTSC video and 720 x 576 for PAL video.

Aspect ratio: 4:3 or 16: 9 (widescreen). Remember that if you want to produce a widescreen DVD, the video should be anamorphic 16:9 (horizontally squeezed).

Frame rate: again this depends on whether your video is PAL or NTSC. Select 25 fps for PAL video and 29.97 fps for NTSC video.

Rate control mode: which rate control mode results in the best quality MPEG-2 file continues to be the subject of hot debate. Very briefly, constant bitrate (CBR) mode encodes the video in such a way that the data rate is approximately constant throughout. The bitrate is specified by the user.

Variable data rate (VBR), on the other hand, allocates a high data rate to demanding shots (those that have a lot of movement and/or a lot of sharp detail) and a lower data rate to simple shots (those in which there is little movement and not much detail). The advantage of VBR encoding is that compression bandwidth is used economically and therefore, in theory, for a given perceived quality, it will result in a smaller file, because no extra data was wasted on shots that don't need it.

I have always used CBR encoding for the simple reason that the videos were never long enough to make the file size an issue.

If you have to fit more than one hour of video onto a DVD, VBR encoding is probably the best option. For best results you should use 2-pass or 3-pass VBR. In the first pass the encoder analyses the video, making decisions on how much datarate each shot needs. After this reconnaissance it does another pass in which it encodes the video, using the decisions it made during the exploratory pass. 3-pass VBR produces even better results, but by all accounts doing more passes is a waste of time. Of course the more passes you do the longer the encoding will take. Slow encoding is probably the only weakness of the Tsunami encoder.

You can see the difference in the data rate characteristics of MPEG-2 files encoded with different methods by using a very useful little application called Bitrate Viewer. If you import your MPEG-2 file into this program it will read it and it will produce a graph of data rate plotted as a function of time. You will notice that even with CBR the data rate, although pretty much constant, does fluctuate. As expected, with VBR encoding the data rate fluctuates widely.

Bitrate: the Bitrate refers to how much data will be used to describe the video. The higher the bitrate, the better quality the video, and the greater the file size will be. Remember that the DVD video standard prescribes a maximum combined data rate for all data streams on the DVD of 10.08 Mb/s.

More importantly, if you are burning your own DVDs on blank media, it is imperative that the total combined data rate of all data streams should not exceed 7 Mb/s. If you use a higher data rate, the video might stutter during playback, because blank DVDs are not as reflective as mass-produced ones, which makes it difficult for the DVD player to keep up with the high data rate.

If you are using uncompressed audio (PCM), remember that its data rate is 1.536 Mb/s, which leaves you with 5500 Mb/s for the video, assuming there are no other data streams. If you use Dolby Digital (AC3) audio, you can have an excellent audio file with a data rate of only 383 kb/s, which would allow you to encode the MPEG 2 video file at a data rate of 6700 Mb per second. Using uncompressed (PCM) audio is a waste of bandwidth – you should use Dolby Digital Audio whenever possible.

I have noticed that the effective data rate of MPEG-2 files encoded by the Tsunami encoder is always lower than the figure you type in the bit rate box. I discovered this with the Bitrate Viewer application mentioned earlier. For this reason, if I want an MPEG-2 file with a data rate of 6500 Mb/s, I select 7 Mb per second. I then scan the file with the Bitrate Viewer to make sure that the real data rate has the required value. There seems to be a systematic discrepancy of approxmately 500 Mb/s between the selected and effective datarates.

If you opted for VBR encoding you will notice that the bitrate field will be greyed out. Click on Setting to the right of the rate control mode menu and choose values for the minimum, average, and maximum data rate. These parameters allow you to exert some control over the VBR encoding process.

Profile & level: choose main profile and main level (MP@ML).

Video format: NTSC or PAL.

Encode mode: choose interlace if the MPEG-2 file will be used in DVD authoring.

YUV format: choose 4:2

DC component precision: choose 10 bits for best results

Motion search of precision: this determines how much time the Tsunami encoder will spend trying to encode the video's motion characteristics efficiently. As always, there is a trade-off between quality and speed. I strongly recommend you go for the highest quality, as this is the Tsunami encoder's biggest strength.

Advanced

Video source type: interlaced (choose de-interlaced if your video is progressive-scan).

Field order: the field order should be bottom field first (field B) for digital video; you should select top field first (field A) if you are encoding analog video. If you get this wrong your MPEG-2 video will exhibit juddery motion.

Source aspect ratio: select 4:3 or 16:9 display. Don't bother specifying frame sizes.

Video arrange method: it doesn't matter what you choose here, providing the frame size you chose in the Video tab matches your video's size.

Filters: leave them alone.

GOP structure

The details of MPEG-2 encoding are beyond the scope of this guide. Let it suffice that you will get excellent results by using the following values:

Number of I pictures in GOP: 1

Number of P pictures in GOP: 5

Number of B pictures in GOP: 2

Output interval of sequence header: 1

Max number of frames in the GOP: choose 15 for PAL video and 18 for NTSC video.

Output bitstream for edit (closed GOP): unchecked

Detect scene change: checked (this will ensure that the cuts in the your video remain clean instead of being damaged by an encoding process that did not recognize them.)

Force picture type setting: unchecked.

Quantize matrix

Choose default in the drop-down menu.

Output YUV data as basic YCbCr not CCIR601: checked, unless this darkens your video, in which case you should uncheck it (I have always had to leave it unchecked - I have been told it depends on your source video file's codec).

Use floating point DCT (while using SSE, always ON): checked

No motion search for still picture part by half pixel: unchecked

Soften block noise: unchecked

That's it for the video settings.

Audio for DVD

There are only two audio formats that are compatible with the DVD standard: PCM (uncompressed) and Dolby Digital (AC3). PCM audio has a data rate of 1.536 Mb/s. It is a shame to waste so much data rate on the audio when you can have the same quality with a data rate of 383 kb per second at the very most. If you're going to be authoring a lot of DVDs, it's worth investing in a good Dolby Digital audio encoder.

At the end of all this you should have a high-quality MPEG-2 video file and an audio file. Import them into your DVD authoring program and proceed from there.