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The difference is bitrate. DVDs were 10 mbit of MPEG-2 while YouTube 480p is 2.5mbit of h264 (or transcodes thereof). These are different encodings so it's not

by Macha 3y ago

The difference is bitrate. DVDs were 10 mbit of MPEG-2 while YouTube 480p is 2.5mbit of h264 (or transcodes thereof). These are different encodings so it's not a 1 to 1 comparison of bitrates as h264 is more efficient, but this article indicates that you'd need 4mbit of h264 (which is closer to that YouTube allocates to 720p video) to match the perceived quality of 10mbit of MPEG-2: https://streaminglearningcenter.com/articles/h264-vs-mpeg-2-quality.html https://streaminglearningcenter.com/articles/h264-vs-mpeg-2-...

ksec 3y ago
I am not sure where you get the 2.5Mbps and 4 Mbps number from because those are very high numbers for streaming ( or even for torrent downloading ) for those resolution and Youtube dont use any where near those number. A quick check shows Youtube only uses around 600Kbps on 720P video. And anywhere between 1.5 to 1.8Mbps for 1080P content. I am guessing their relatively low quality compared to their bitrate is because their encoding process optimise for encoding time rather than quality per bit simply because of the volume they have per day.
- Macha 3y ago
  2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zippy=%2Cbitrate https://support.google.com/youtube/answer/1722171?hl=en#zipp... They will then transcode it to h265, or webm which uses even less bandwidth, but I'm giving them the benefit of the doubt here and assuming they target their transcoding setup to preserve as much quality as they recommend providing them. And of course this is VBR not CBR, so some scenes will use less. 4mbps is the linked article description of where h264 matches DVD quality. Yes, 4mbps is more than most streaming sites will give for 480p. This does mean that most streaming sites are inferior to DVDs at 480p. The fact that most streaming sites use less bitrate than a DVD-equivalent quality is therefore not surprising, giving that people have noticed that exact fact. Streaming sites do not pick their bitrate to maximise quality given a fixed maximum filesize, so it's not surprising that they choose a lower bitrate (and therefore lower quality) than DVDs. They're instead optimizing for things like their server costs, time to playback start, or the ability to perform uninterrupted playback over the internet connection of users resorting to these lower resolution settings.
  - ksec 3y ago
    >2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zipp https://support.google.com/youtube/answer/1722171?hl=en#zipp... That is for uploading. They will transcode your H.264 file when you upload it regardless of bitrate.
    - Macha 3y ago
      It's like you didn't even read the very next sentence.
      - ksec 3y ago
        You said transcode to H.265. And they dont transcode to H.265 or HEVC. ( Apart from some edge case of 360 degree video ) And your original claims of YouTube using 2.5Mbps and 4Mbps. Go and find me clip with those bitrate?
        Macha 3y ago
        Ok, sure, they also produce extra h264 files at various resolutions and quality levels. Transcoding can't invent quality that wasn't there in the input, so I don't see how that changes anything. That 2.5mbit/s upload they accept is therefore the ceiling.

by Macha 3y ago

ksec 3y ago

I am not sure where you get the 2.5Mbps and 4 Mbps number from because those are very high numbers for streaming ( or even for torrent downloading ) for those resolution and Youtube dont use any where near those number. A quick check shows Youtube only uses around 600Kbps on 720P video. And anywhere between 1.5 to 1.8Mbps for 1080P content. I am guessing their relatively low quality compared to their bitrate is because their encoding process optimise for encoding time rather than quality per bit simply because of the volume they have per day.

Macha 3y ago
2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zippy=%2Cbitrate https://support.google.com/youtube/answer/1722171?hl=en#zipp... They will then transcode it to h265, or webm which uses even less bandwidth, but I'm giving them the benefit of the doubt here and assuming they target their transcoding setup to preserve as much quality as they recommend providing them. And of course this is VBR not CBR, so some scenes will use less. 4mbps is the linked article description of where h264 matches DVD quality. Yes, 4mbps is more than most streaming sites will give for 480p. This does mean that most streaming sites are inferior to DVDs at 480p. The fact that most streaming sites use less bitrate than a DVD-equivalent quality is therefore not surprising, giving that people have noticed that exact fact. Streaming sites do not pick their bitrate to maximise quality given a fixed maximum filesize, so it's not surprising that they choose a lower bitrate (and therefore lower quality) than DVDs. They're instead optimizing for things like their server costs, time to playback start, or the ability to perform uninterrupted playback over the internet connection of users resorting to these lower resolution settings.
- ksec 3y ago
  >2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zipp https://support.google.com/youtube/answer/1722171?hl=en#zipp... That is for uploading. They will transcode your H.264 file when you upload it regardless of bitrate.
  - Macha 3y ago
    It's like you didn't even read the very next sentence.
    - ksec 3y ago
      You said transcode to H.265. And they dont transcode to H.265 or HEVC. ( Apart from some edge case of 360 degree video ) And your original claims of YouTube using 2.5Mbps and 4Mbps. Go and find me clip with those bitrate?
      - Macha 3y ago
        Ok, sure, they also produce extra h264 files at various resolutions and quality levels. Transcoding can't invent quality that wasn't there in the input, so I don't see how that changes anything. That 2.5mbit/s upload they accept is therefore the ceiling.