Convert any Movie to DVD Video
- Why another article about this argument? There is a plethora of articles, man pages, blog entries on the Internet about how to convert any
- movie to a standard DVD Video viewable to any hardware DVD player. But most of those pages actually focus on one problem. The point of this
- article is to summarize most the knowledge necessary in only one place.
The parts of a DVD
For our purposes every movie in the DVD has one video track, at least one audio track, possibly subtitles. We will begin making a simple DVD that just start the movie we put in the DVD player, without any menu. If there is more than one movie you can select them using the chapter function of the DVD player.
Standard compliant DVD videos have well defined an precise video requirement. The aspect ratio can be '16/9' or '4/3', the available resolutions change if you are making a Pal or a NTSC DVD. The two standards also have different frame ratios.
DVDs do not use square pixels, the pixels are rectangular: while the movie has a certain resolution the player have to show it as it were another deforming the pixels. The table show the real resolution and how the player shows it.
NTSC DVD, framerate: 30000/1001 (29.97) or 24000/1001 (23.97) Resolution Displayed as 720x480 720x540 (4/3) or 854/480 (16/9) 704x480 720x528 (4/3) 352x480 640x480 (4/3) 352x240 352x264 (4/3) PAL DVD, framerate: 25 Resolution Displayed as 720x576 768x576 (4/3) or 1024/576 (16/9) 704x576 768x576 (4/3) 352x576 768x576 (4/3) 352x288 384x288 (4/3)
As you can read the 4/3 aspect ratio have 4 resolutions, the 16/9 only one. The Ntsc standard gives you two kind of frame rate while Pal only one.
Depending of the country you live on, you have to decide between Ntsc or Pal. In order to decide ratio and resolution you have to see your input movie.
Play you input movie with mplayer (of mplayer package), ensure that mplayer plays exactly what you want to put in the DVD. You might consider options like -ss. --endpos or -chapter.
mplayer show lines like:
Movie-Aspect is 1.39:1 - prescaling to correct movie aspect. VO: [xv] 512x368 => 512x368 Planar YV12
Where gives you the aspect ratio and the resolution. In this very example the ratio is 1.39:1 that is quite similar to 4/3 (as is 1.333:1), while the resolution is 512x368 we can put it in a 704x576 Pal DVD or 704x480 Ntsc DVD.
This is fine and good if the input does not have black borders or if the input file have exactly the aspect ratio of 4/3 or 16/9. Otherwise there is some intermediate step to do.
Removing the black borders
If the input file has black borders and its aspect ratio is not 4/3 or 16/9 you have to remove the black border and consider the 'real' resolution and the 'real' aspect ratio. mplayer has a feature to detect the black border in order to remove it: the cropdetect video filter. Play the movie with -vf cropdetect, seek in the movie a bright part where the black borders are easily visible. mplayer will give you an output with the correct crop values. Example:
... Movie-Aspect is 1.50:1 - prescaling to correct movie aspect. VO: [xv] 720x480 => 720x480 Planar YV12 ... [CROP] Crop area: X: 0..719 Y: 38..440 (-vf crop=720:400:0:40).% 0 0 [CROP] Crop area: X: 0..719 Y: 38..440 (-vf crop=720:400:0:40).% 0 0 [CROP] Crop area: X: 0..719 Y: 38..440 (-vf crop=720:400:0:40).% 0 0 ...
This movie have 40 pixels of black border and its aspect ratio is 1.50. So we sought a bright zone and mplayer said us the correct values for the crop video filter: in this case 720:400:0:40.
Playing again the movie with -vf crop=720:400:0:40 we see the real resolution, unfortunately mplayer will show the old aspect ratio and we have to calculate the real one by hand:
Movie-Aspect is 1.50:1 - prescaling to correct movie aspect. VO: [xv] 720x400 => 720x400 Planar YV12
The aspect ratio is actually 720/400 = 1.8; a ratio of 1.8 means we have to use 16/9 (as it is 1.777)
Obtaining the correct aspect ratio
We have movie without black borders with the wrong aspect ratio as DVDs accept only 16/9 or 4/3. Luckily mplayer has another video filter that puts the correct black borders to obtain the correct aspect ratio. The filter is expand. Lets continue the previous example:
mplayer movie.mov -vf crop=720:400:0:40,expand=:::::16/9:16
mplayer will display the movie with a small black border (we passed from to 1.8 to 1.777 after all). All heading the colons are necessary because the filter would accept many other parameters we leave to default, the trailing :16 instead is necessary because for encoding reasons the black borders must be high (large) a multiple of 16.
Reaching a valid resolution
Now we have to decide the resolution we will use. Of course if we selected the 16/9 aspect ratio we will have only one choice (720x576 for Pal or 720x480 for Ntsc), but if we selected the 4/3 aspect ratio we have to decide. Usually the best selection is the smallest resolution that contains the original movie after removing the black borders. For example a 4/3 movie of 640x480 should be put in 704x480 Ntsc or 704x576 Pal. To continue the previous example we will use 720x576 Pal.
The video filter chain becomes: -vf crop=720:400:0:40,expand=:::::4/3:16,scale=720:576,dsize=1024:576 where we scaled to the correct resolution in scale and set the display resolution in dsize following the table.
If mplayer shows something like VO: [xv] 720x576 => 1024x576 Planar YV12 where the first pair is the resolution, the second pair is the displayed resolution and the movie is displayed correctly (no oval heads for example) we are done.
Encoding the video
We finally convinced mplayer to display our video with a aspect ratio of 4/3 or 16/9 keeping the correct aspect ratio in one of the DVD compliant resolutions.
It is finally time of encode the video in a file good for DVD video. We will use mencoder (of mplayer package), mplayer and mencoder share the video filers, so the -vf line we calculated until now will be used to have a fine mpeg2 file.
There is one last thing to decide, the average bitrate of movie. A compliant DVD can have a maximum bitrate of 9800 bits per second including sound tracks and subtitles. The video itself usually uses only 4000-5000 kbits per seconds in average. mencoder takes the meaning of average very seriously, so much you can assume that:
(average bitrate) * (movie length in seconds) = (total of bits)
And knowing how many bits you have in the DVD you can calculate your bitrate with great precision.
Kind of DVD # of bits DVD-R SL 37658558464 DVD+R SL 37602983936 DVD-R DL 68349329408 DVD+R DL 68383932416
For example if you have a 2 hours movie (7200 seconds), a single 448 kbits per seconds audio track (usual value for 6 channels audio) and a DVD-R SL you might calculate:
37658558464 / 7200 - 448000 = 4782355
There is probably some space wastage in the DVD structure, but we can use 4500 kbits and be fairly safe.
The encoding is made in two passages, the first is about getting information about the movie structure in order to know where the encoder should use more bits (high action scenes) and where it should use less bits (calm or slow paced scenes) in order to use exactly the bits you asked for with the best quality.
Here the commands, as you can understand from the || exit, it is meant to be written in a file:
rm divx2pass.log nice -19 mencoder -nosound -ovc lavc -of rawvideo \ -vf crop=720:400:0:40,expand=:::::16/9:16,scale=720:576,dsize=1024:576,harddup -ofps 25 \ -lavcopts vcodec=mpeg2video:turbo:vpass=1:vrc_buf_size=1835:vrc_maxrate=9800\ :vbitrate=4500:keyint=15:vstrict=0:aspect=16/9 -o /dev/null \ movie.mov || exit nice -19 mencoder -nosound -ovc lavc -of rawvideo \ -vf crop=720:400:0:40,expand=:::::16/9:16,scale=720:576,dsize=1024:576,harddup -ofps 25 \ -lavcopts vcodec=mpeg2video:vpass=2:vrc_buf_size=1835:vrc_maxrate=9800\ :vbitrate=4500:keyint=15:trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=2\ :predia=2:cbp:mv0:lmin=1:dc=10:vstrict=0:aspect=16/9 \ movie.mov -o movie_video_track.m2v || exit
Things to notice:
- there is the video filters chain we calculated until now with the adding of harddup. A necessary filter to obtain standard compliant DVD videos;
- the bitrate we decided (4500) is the value that appears in vbitrate value;
- the aspect ratio appears in the aspect value;
- the -ofps 25 option is there because we wanted a Pal DVD, if you wanted a Ntsc DVD you had to put -ofps 30000/1001;
- the first passage throws away the video output; the passage is there only to make the information file divx2pass.log;
- the input file movie.mov can be replaced with everything mplayer can read, it is of course only a placeholder;
- there is no sound at the moment;
- the output is a raw video stream.
All the other values are more or less fixed for an high quality conversion, you can (and should) read about in the mencoder man page.
Note: the filter chain shown here is complete in the sense we had to make every passage. If you had an input file already of 16/9 ratio for example you would have only -vf scale=720:576,dsize=1024:576,harddup; if you had a input file of the wrong ratio but without black borders you would have only -vf expand=:::::4/3:16,scale=720:576,dsize=1024:576,harddup; the bare minimum is -vf harddup if you had a movie of a correct resolution and ratio.
Save this commands in a text file and in the shell execute sh filename, the execution of those two commands might take long. But once finished you will have a video stream good for DVD video.
If you have more than one video file (like first part of the movie in a file and the second part in another file) you have to encode both following this instructions, we will put both in the DVD when we will author the DVD.