{"id":2950,"date":"2010-10-14T22:49:25","date_gmt":"2010-10-15T05:49:25","guid":{"rendered":"http:\/\/multimedia.cx\/eggs\/?p=2950"},"modified":"2011-12-02T11:38:57","modified_gmt":"2011-12-02T19:38:57","slug":"gallery-of-vp8-encoding-naivete","status":"publish","type":"post","link":"https:\/\/multimedia.cx\/eggs\/gallery-of-vp8-encoding-naivete\/","title":{"rendered":"Gallery of VP8 Encoding Naivete"},"content":{"rendered":"

I’ve been toiling away as a multimedia technology generalist for so long that it’s easy for me to forget that not everyone is as versed in the minutiae of the domain as I am. But I recently experienced what it’s like to be such an outsider when I posted about my toy VP8 encoder<\/a>, expressing that it’s one of the hardest things I have ever tried to do. I heard from a number of people who do have extensive experience in video encoding, particularly with the H.264 and VP8 codecs. Their reactions were predictable: What’s so hard?<\/em> Look, you might be a little too immersed in the area to really understand a relative beginner’s perspective.<\/p>\n

And to all the people who suggested that I should get the encoder into FFmpeg<\/a> ASAP: Are you crazy?!<\/em> Did you see<\/em> what the first pass of the encoder produced? Do you have lower standards than even I do?<\/p>\n


\n\"\"
\n<\/center><\/p>\n

Not Giving Up<\/strong>
\nI worked a little more on the toy encoder. Remember that the above image is what I’m hoping to encode somewhat faithfully for this experiment. In my first pass, I attempted vertical prediction for all planes. For my next pass, I forced the chroma planes to mid-level (which results in a greyscale image) and played with the 16×16 luma prediction modes. When implementing an extremely naive algorithm to decide which 16×16 prediction mode would be the best for a particular block, this is what the program produced:<\/p>\n


\n\"\"
\n<\/center><\/p>\n

For fun, here is what the image encodes to when forcing various prediction modes:
\n<\/p>\n

I think the DC-only prediction mode actually looks a little better than the image that the naive algorithm produced:<\/p>\n


\n\"\"
\n<\/center><\/p>\n

Vertical 16×16 prediction, similar to the image from the last post (just in black and white):
\n


\n\"\"
\n<\/center><\/p>\n

Horizontal 16×16 prediction:
\n


\n\"\"
\n<\/center><\/p>\n

This is the 16×16 prediction mode unique to VP8, the TrueMotion mode (based on On2\/Duck’s very first video codec<\/a>):
\n


\n\"\"
\n<\/center><\/p>\n

Wow, these encodings really bring down the cheerful tone of the original image. <\/p>\n

Next Steps<\/strong>
\nI have little reason to believe that I am encoding and subsequently reconstructing the image correctly (i.e., error is likely propagating through the entire encoding). If I have time, the next step is to validate my reconstruction against the encoder. Then I need to get the entropy considerations correct so that I actually get some compression out of this format.<\/p>\n","protected":false},"excerpt":{"rendered":"

I worked a little more on my toy VP8 encoder; here are some interesting pictures from my efforts.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[219],"tags":[],"class_list":["post-2950","post","type-post","status-publish","format-standard","hentry","category-vp8"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/posts\/2950","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/comments?post=2950"}],"version-history":[{"count":8,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/posts\/2950\/revisions"}],"predecessor-version":[{"id":3646,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/posts\/2950\/revisions\/3646"}],"wp:attachment":[{"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/media?parent=2950"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/categories?post=2950"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/multimedia.cx\/eggs\/wp-json\/wp\/v2\/tags?post=2950"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}