Basic Video Encoding Question

[crosen]

What standard(s) describe the raw video bit streams that are input to and output from typical encoders (i.e mpeg4-2, wmv9, etc.?)

[edDV]

What standard(s) describe the raw video bit streams that are input to and output from typical encoders (i.e mpeg4-2, wmv9, etc.?)

Need more context. What do you have and what do you want to do?

[crosen]

I'm just trying to fill a whole in my understanding of the subject. I don't understand how a device (i.e. computer, DVD player, etc.) can render the video from, say, an MPEG-4 file unless it knows not only how to decode an MPEG-4 file to an uncompressed bit stream, but also how to interpret that subsequent bit stream as video frames. Yet, I can't find any material that explains the specs/standards for that interpretation?

[jagabo]

The decompressors produce output frames in one of several defined standard formats like RGB24, YV12, YUY2. Conversely, the compressors accept input in similar formats.

[edDV]

I'm just trying to fill a whole in my understanding of the subject. I don't understand how a device (i.e. computer, DVD player, etc.) can render the video from, say, an MPEG-4 file unless it knows not only how to decode an MPEG-4 file to an uncompressed bit stream, but also how to interpret that subsequent bit stream as video frames. Yet, I can't find any material that explains the specs/standards for that interpretation?

Mpeg2 (DVD) or MPeg4 files converted to uncompressed YCbCr or RGB would be a decode. The reference specs for MPeg2 or MPeg4 define the decode mechanism. MPeg in general consists of a sequence of digital frames organized as GOPs (group of pictures).
http://www.webopedia.com/term/m/mpeg.html
http://en.wikipedia.org/wiki/MPEG-2

[minidv2dvd]

codec - compressor/decompressor - like jag says they convert uncompressed to compressed and back out the other way.

[crosen]

great, jagabo, thank you much - that's just what i was looking for.

[edDV]

See http://www.fourcc.org/ for uncompressed format descriptions.

[crosen]

thanks, edDV, that's very useful.

[jagabo]

For display purposes under Windows the most common format are RGB24, RGB32, YV12, and YUY2 because graphics card can display those directly.