Very low bitrate encoding for DVD

[Alex-Kid]

Hi, I'm trying to encode some kind of "audio player" with on screen lyrics for DVD playback. Here is a screenshot:

http://i42.tinypic.com/34driiw.jpg

The problem is that the the DVD lasts more than 10 hours, so I'm aiming for DVD-DL, and audio bitrate is 1536 kbps (LPCM, high quality audio), that leaves me with about 275 kbps for Full D1 video encoding.

I've tried with HCEnc but I couldn't find any good quality settings. Everything looks very blocky, even with low bitrate matrices. But the video have very little motion, only on especific areas (playback bar and running time), so I assume it doesn't need much bitrate and what I want to encode is possible with a good quality. Here is a screenshot of what I got with HCEnc:

http://i43.tinypic.com/zvvl10.jpg

So, is there any way to achieve what I want to do?

[Rumbah]

I guess the problem is that the max GOP for DVD is 15 so you have about 2 I frames per second and the P and B frames so I guess that's a little low for that video.

So you could either reduce the resolution to half or quarter NTSC/PAL or compress the audio track with a high bitrate.

[Alex-Kid]

That sounds interesting. 275 kbps (34375 bytes) for 2 I-frames is like 2 JPGs of less than 17180 bytes, and for a 720x480 px picture is obviously low quality. Thanks for pointing me that.

Then I think the best solution is to increase the GOP size, so it won't fit for DVD compliancy. So, now I need to know if my DVD player will play a DVD with higher GOP size than the standard allows. I remember the early days of KVCD/KDVD and, if I'm right, that "standard" allowed higher GOP size.

-----EDIT-----

I recently increased the GOP size en HCEnc, but it has an upper limit of 36: and still looks bad. So I tried good ol' TMPGEnc and did the magic with a GOP size of 202 (about 6 seconds and 67 P-frames per GOP). But TMPGEnc encodes are too soft, so I think I'm gonna try another encoder that handles long GOP sizes. Maybe ffmpeg?

[TheSkiller]

Apart from the encoding, no offense but while looking OK when viewed on a computer, your audio player will look quite amateurish when viewed on a TV:

- title safe area ignored (text will be cropped because it's too close to the frame edges)
- line twitter
- font size is too small


I'd be surprised if you happen to find a hardware player that will playback a GOP of 202 pictures in DVD/MPEG2 mode. Forward/Backward Scan would be a pain in the butt anyway.

If I was you I would probably go for CIF (352x240) or encode the audio at 384 Kbit/s MP2 or AC3.

[Biggiesized]

Definitely drop the audio down to stereo AC-3 at 192 kb/s.

[Ghitulescu]

Go with fewer titles (less duration).
The maximum duration a hardware DVD-recorder goes is, for exactly there reasons, of only 8 hours (also at half-D1 or even VCD).
The only part "in motion" seems to be the progress bar, normally this shouldn't pose any problems to any encoder at this bitrate - you may want to make it "discontinuous" à la Windows 98 (with squares instead of a continuous band) updated say every second. Your problem seems also to be that the I frames (which have to be compressed in full) require a much higher bitrate, since the image is extremely complicated. And this is repeated almost twice every second, which will raise the average bitrate above the chosen value.

[Alex-Kid]

Thanks everyone for your suggestions.

I tried encoding with ffmpeg with settings used in TMPGEnc and did a better job, the video got clean at last. However I couldn't author the DVD with resulting file, so I think I'll have to look for other alternatives.

Greetings

By ALEX-KID

[SquallMX]

Replacing the background with black could help. Encoding the audio as AC3 320 Kbps is also a good choice.