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There's no such thing as a codec that looks good or bad in an absolute sense. Codecs boil down to a quality versus bitrate curve. And starving them always loo

There's no such thing as a codec that looks good or bad in an absolute sense. Codecs boil down to a quality versus bitrate curve. And starving them always looks bad. While the most common kind of artifact will shift between standards, significant artifacts are fundamentally bitrate issues or encoder bugs. If you gave DVD levels of bits-per-pixel to MPEG-4 ASP you could get something that looks nearly perfect.

daneel_w 2mo ago
> There's no such thing as a codec that looks good or bad in an absolute sense. There are plenty of examples of both awful codecs (software; encoders) and of digital audio/video standards (e.g. Vorbis and MPEG-4 ASP) suffering from material limitations. > If you gave DVD levels of bits-per-pixel to MPEG-4 ASP you could get something that looks nearly perfect. No. Not even if the source is encoded by XviD. Not all problems can be solved by throwing higher bitrate at it. The ASP only supports 4:2:0 chroma subsampling, which is the largest of several shortcomings contributing to the limited quality you can achieve with ASP video material. People on at least an intermediate knowledge level of digital video know what a damning problem 4:2:0 subsampling is and how heavy a penalty it incurs on color and clarity. Your comments mostly hold a suggestion that you kinda have some rough idea about digital video. And that's OK. MPEG-4 SSTP is a very different matter, but that's not what DivX and XviD encodes.
- Dylan16807 2mo ago
  I should have added "general purpose". I know there are restrained encoders for specific situations. Can you list a few of your examples for video? And I don't understand the other example you did mention, isn't vorbis more than enough at high bitrate? 4:2:0 is just fine for video. It is not a heavy penalty. It's OK for you to be rough about this. More seriously, if it's good enough for bluray and UHD bluray then it's fine.
  - daneel_w 2mo ago
    Yeah sure, a few example that spring to mind would be... Poor encoder: FAAC/FAAC2, the first open-source encoder for AAC audio, produce terrible audio no matter how much bitrate you let it work with. The AAC standard itself facilitates crisp audio quality at low bitrates, as heard with e.g. Apple's Core Audio AAC encoder or Nero AAC. Poor encoder: Xing, a popular MP3 encoder of the early 2000s, was similarly infamous for producing chirpy and slurry audio even at or above 192 kbps, while bona fide MP3 encoders like LAME do far better on less. Poor encoder: NVENC, Nvidia's on-GPU hardware video encoder, produce very poor H.264 video even at 8-10 mbps, even on the current 8th and 9th generation (RTX 40/50 series). Good H.264 encoders like x264 is capable of producing excellent FullHD video at just 2-3 mbps. Poor standard: Vorbis is a good example of a spec whose limits/mistakes make it impossible to preserve certain combinations of frequencies, resulting in brief passages where parts of the reproduced spectrum deflates, making some music sound as if it lost its breath, so to speak. When fed certain "triggering" audio content designed to expose problems in the spec, Xiph's reference Vorbis encoder will produce ringing sounds. Interestingly also the MP3 spec has similar limitations where certain frequency combinations (usually towards the lower and upper ends) will reproduce with quantized amplitude, even when encoded with LAME, though the outcome is nowhere near as pronounced as it can be with Vorbis. Poor standard: MPEG-4 ASP, being limited to 4:2:0 chroma subsampling and PAL/NTSC resolutions. My beef with 4:2:0 is because of how harsh it is on low-resolution content. MPEG-4 ASP being limited to a maximum of 720x576, and the 4:2:0 chroma coverage being only a quarter of that, is the reason why DivX/XviD content is smudgy even with reproduction filters. On FullHD content a 4:2:0 grid has almost three times higher resolution, which I agree works out on both still scenes and slow panning (the two scenarios where low chroma resolution makes itself most reminded).
    - Dylan16807 2mo ago
      Oh I didn't mean to waste your time on poor encoders. I'm sure there's many of those. I mean actual codecs that have a problem, that make it impossible to do good quality. > Vorbis is a good example of a spec whose limits/mistakes make it impossible to preserve certain combinations of frequencies, resulting in brief passages where parts of the reproduced spectrum deflates, making some music sound as if it lost its breath, so to speak. So the people that talk about bitrates where it's transparent are basically delusional? > Poor standard: MPEG-4 ASP, being limited to 4:2:0 chroma subsampling and PAL/NTSC resolutions. That makes a lot of sense, I had no idea it was limited to those resolutions. Thanks for the time explaining those.

daneel_w 2mo ago

> There's no such thing as a codec that looks good or bad in an absolute sense. There are plenty of examples of both awful codecs (software; encoders) and of digital audio/video standards (e.g. Vorbis and MPEG-4 ASP) suffering from material limitations. > If you gave DVD levels of bits-per-pixel to MPEG-4 ASP you could get something that looks nearly perfect. No. Not even if the source is encoded by XviD. Not all problems can be solved by throwing higher bitrate at it. The ASP only supports 4:2:0 chroma subsampling, which is the largest of several shortcomings contributing to the limited quality you can achieve with ASP video material. People on at least an intermediate knowledge level of digital video know what a damning problem 4:2:0 subsampling is and how heavy a penalty it incurs on color and clarity. Your comments mostly hold a suggestion that you kinda have some rough idea about digital video. And that's OK. MPEG-4 SSTP is a very different matter, but that's not what DivX and XviD encodes.

Dylan16807 2mo ago
I should have added "general purpose". I know there are restrained encoders for specific situations. Can you list a few of your examples for video? And I don't understand the other example you did mention, isn't vorbis more than enough at high bitrate? 4:2:0 is just fine for video. It is not a heavy penalty. It's OK for you to be rough about this. More seriously, if it's good enough for bluray and UHD bluray then it's fine.
- daneel_w 2mo ago
  Yeah sure, a few example that spring to mind would be... Poor encoder: FAAC/FAAC2, the first open-source encoder for AAC audio, produce terrible audio no matter how much bitrate you let it work with. The AAC standard itself facilitates crisp audio quality at low bitrates, as heard with e.g. Apple's Core Audio AAC encoder or Nero AAC. Poor encoder: Xing, a popular MP3 encoder of the early 2000s, was similarly infamous for producing chirpy and slurry audio even at or above 192 kbps, while bona fide MP3 encoders like LAME do far better on less. Poor encoder: NVENC, Nvidia's on-GPU hardware video encoder, produce very poor H.264 video even at 8-10 mbps, even on the current 8th and 9th generation (RTX 40/50 series). Good H.264 encoders like x264 is capable of producing excellent FullHD video at just 2-3 mbps. Poor standard: Vorbis is a good example of a spec whose limits/mistakes make it impossible to preserve certain combinations of frequencies, resulting in brief passages where parts of the reproduced spectrum deflates, making some music sound as if it lost its breath, so to speak. When fed certain "triggering" audio content designed to expose problems in the spec, Xiph's reference Vorbis encoder will produce ringing sounds. Interestingly also the MP3 spec has similar limitations where certain frequency combinations (usually towards the lower and upper ends) will reproduce with quantized amplitude, even when encoded with LAME, though the outcome is nowhere near as pronounced as it can be with Vorbis. Poor standard: MPEG-4 ASP, being limited to 4:2:0 chroma subsampling and PAL/NTSC resolutions. My beef with 4:2:0 is because of how harsh it is on low-resolution content. MPEG-4 ASP being limited to a maximum of 720x576, and the 4:2:0 chroma coverage being only a quarter of that, is the reason why DivX/XviD content is smudgy even with reproduction filters. On FullHD content a 4:2:0 grid has almost three times higher resolution, which I agree works out on both still scenes and slow panning (the two scenarios where low chroma resolution makes itself most reminded).
  - Dylan16807 2mo ago
    Oh I didn't mean to waste your time on poor encoders. I'm sure there's many of those. I mean actual codecs that have a problem, that make it impossible to do good quality. > Vorbis is a good example of a spec whose limits/mistakes make it impossible to preserve certain combinations of frequencies, resulting in brief passages where parts of the reproduced spectrum deflates, making some music sound as if it lost its breath, so to speak. So the people that talk about bitrates where it's transparent are basically delusional? > Poor standard: MPEG-4 ASP, being limited to 4:2:0 chroma subsampling and PAL/NTSC resolutions. That makes a lot of sense, I had no idea it was limited to those resolutions. Thanks for the time explaining those.