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What’s the best format for storing digital movies? | Technology | The Guardian

What format is a dvd movie in

Video What format is a dvd movie in

Having a bit of a clean up, I thought I’d copy some old dvd’s to free up space, like I did with my music collection a few years ago. i planned to store the content on my nas to stream/sync to a variety of devices including a couple of dlna compatible smart tvs, ipad, iphone, xbox 360 and obviously pcs. I’m not too concerned about file size and would prefer the best possible video and audio quality. I’d also like to preserve any multi-channel audio (ie 5.1 surround sound). what file formats would you recommend to allow me to be flexible and future proof as much as possible? I’ve already tried a couple of dvds saved as .mpg, which work fine with my smart tvs. i tried importing them into itunes to sync with my ipad, but itunes doesn’t seem to like them.

scott martin

Most DVDs store movies in the standard MPEG-2 (also known as H.262) format defined by the Moving Picture Experts Group, although MPEG-1 is also supported. the video is saved in vob (video object) files. the video is interlaced for display on common televisions. The result is a resolution of 720 x 576 pixels at 25 frames per second, for 50hz TVs, or a resolution of 720 x 480 pixels at 29.97 frames per second, for 60hz TVs.

mpeg-2 was the obvious choice for dvds, as it was already used for broadcast and cable television. the 720 x 480 format comes from the ntsc television system in america and the 720 x 576 from pal in europe.

iso or mpeg?

if you want to keep everything on a dvd, then the simplest option is to copy the entire disc as an iso disc image. you can burn this copy to another dvd for backup purposes. You can also play the iso disc image with a software dvd player, including videolan’s vlc, or copy it with the dvd ripping software of your choice.

what you’ve done so far is rip a couple of dvd’s to mpeg-2 (.mpg), so you can have the full original video, but deinterlaced, so now it’s in the progressive display format you use Computer. HD monitors and televisions. however, you may have missed some extras, including vmg (video manager) files, subtitles, hidden files, ads, and alternate audio formats. DVDs can have audio tracks in PCM, DTS, MPEG-1 Audio Layer II (MP2), or Dolby Digital (AC-3) formats. mp2 and ac-3 are the most common, and if you have to choose one of them, choose ac-3. it’s much more efficient (smaller files) and sounds better than mp2 which is old but sadly still used on old dab radios in britain.

For the future, mpeg-2 files are the next best thing to iso images, and I don’t see a time when PCs can’t play them. just like with mp3 audio files, there are just too many.

the next generation

computers and processors have become cheaper and much more powerful since mpeg-2 was specified in the 1990s. this means that we can now use much higher levels of compression to reduce file sizes and still decode them fast enough to maintain the frame rate. This led to the Blu-ray optical disc format, which requires support for two new video standards: MPEG-4 AVC (Advanced Video Coding) and VC-1, the latter based on Microsoft’s WMV-9. some of the early blu-ray discs actually used mpeg-2, since that was the basis for digital production at the time. however, h.264/mpeg-4 part 10 avc, commonly known as h.264, is the most widely used format.

blu-ray movies generally come in 16:9 widescreen resolutions of 1280 x 720 pixels, which is known as hd (high definition) or 720p, or 1920 x 1080 pixels, which is full hd or 1080p , where p means “progressive”. blu-ray also allows the use of interlaced video and 4:3 dvd formats for backward compatibility. hd tvs will deinterlace videos automatically.

video now consumes a lot of space, so both dvds and bds use lossy compression to reduce file sizes. mpeg-2 and mpeg-4 files are equivalent to mp3 audio files in that sense. and, as you know, “transcoding” from one lossy format to another involves a loss of quality. it is something to avoid if possible, and if not, to do only once.

Fortunately, this is usually not a problem if you lower the resolution of the movie, for example, if you convert a video from 1080p to 720p to get a much smaller file size, or if you watch it on a smaller screen. can be a problem if you are “upscaling” a dvd movie to 720p or 1080p.

movies for ipads and iphones

You don’t have many options if you want to use apple itunes and watch movies natively on an ipad or iphone. apple keeps things simple by removing dozens of popular alternatives (avi, wmv, divx, xvid, flv, mkv, etc) and only allowing two true digital video options: mpeg-4 at 640 x 480 pixels and h.264 at up to 720p on most iPads and up to 1080p on iPad mini and iPad Air. both formats are mpeg-4, what is the difference? mpeg-4 comes in many varieties and h.264 is actually mpeg-4 avc part 10.

The alternative is to use a third party video player, such as Videolan’s open source vlc for ios. the website says that it “can play all your movies and shows in most formats directly without conversion” and it works with itunes.

if you decide to convert files, it depends on your dvds and your iphone and ipad. Download one of the free video converters and transcode your 720 x 576 MPEG-2 movies to 640 x 480 MPEG-4 movies, which iTunes should gladly accept. if you have widescreen movies i would convert them to h.264/avc in 720p format. You might get a little more quality if your iPad supports 1080p, but on such a small screen, there won’t be enough of a difference to justify the much larger file sizes and longer transcode times. (I don’t have an iPad, so I’m basing this opinion on using PCs with much larger screens.)

transcoding software

I have no idea what programs do the best job of transcoding movies for ios, but there are so few options that it should be a completely automated process. maybe the readers can recommend something. Otherwise, you can always use one of the free video transcoders that handle the full range of different file formats, codecs, resolutions, frame rates, bit rates, etc. examples include super ©, which is slow and ugly, and handbrake, which is rather clumsy, as well as fancier programs like xmedia recode and media coder. you may also find avidemux useful for editing. try downloading some programs and see what works for you.

In defense of super and handbrake, I’ve used them for years and somehow got decent results out of them. I couldn’t achieve that in my brief media encoder test, although I did get a good conversion my first time with xmedia recode. also, it might be better to use vidcoder instead of handbrake: it’s easier to use and uses handbrake to do the transcoding.

With Audio CDs, you can use Exact Copy Audio and FLAC, the free lossless audio codec, to make perfect digital copies that you can leave to your grandkids, who can convert them to whatever format is popular at the time. with dvds, you don’t get a perfect copy, just a lossy video file, so an iso is the safest option for the future. however, an mpeg-2 file that matches the original (only in a different wrapper, so to speak) is almost as good. if you are going to transcode mpeg-2 into something more modern, then h.264/mpeg-4 avc is probably the best option, and the files should be about half the size. whether they’ll be good enough for the 4k (3840 x 2160 pixels) screens we’ll all be using in a few years is another question.

the ultraviolet solution

If you’re ripping commercial cds or blu-rays, you should keep the original discs in a safe place. these discs show that you own the originals and that you have reused them for your convenience, not pirated or downloaded them. ideally, movie studios would make digital copies available online, either for free or for a reasonable fee. the industry now does this with its ultraviolet system. If you buy DVD or Blu-ray discs with UV stickers, you also get access to a cloud version that you can stream to different devices or download.

In the US, Walmart and some other stores offer disc-to-digital upgrades for some movies. you take your dvds and bds to the store and pay $2 for a digital copy, which is actually stored by vudu. you keep the dvds. it’s faster and much more convenient than copying them yourself, and of course the quality is excellent. haven’t seen this promoted in the uk, although findanyfilm.com is uv compliant, and tesco has offered buyers free digital copies through their blinkbox service.

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