[FFmpeg-user] 4k conversion with hevc

Rodney Baker rodney.baker at iinet.net.au
Thu Aug 16 15:20:05 EEST 2018

On Thursday, 16 August 2018 20:59:27 ACST Josh Blagden wrote:
> I don’t see why not. An MP4 file is most likely to contain an MPEG-4 video
> stream, so it’ll be fine; it’ll take a while depending on your hardware,
> but it can be done. Well, as long as we’re not talking about DRM-protected
> videos from iTunes.
> By the way, MP4 and MKV are just containers. HEVC, MPEG-2, MPEG-3, and VC-1
> are codecs. Codecs go inside containers.  I actually just found out about
> that distinction about six months ago.
> Josh Blagden

You're almost right. 

Forgive me for being pedantic, but CODEC stands for enCODer/DECoder, so the 
codec is what encodes and decodes the stream(s). Encoded streams (the type is 
generally named after the codec that produced them) go inside containers.

The workflow is:
[RAW video -> Video Codec (produces an encoded video stream) || RAW audio -> 
Audio Codec (produces an encoded audio stream)] -> Multiplexer (multiplexes the 
streams and encapsulates them into the container format) -> output file. 

For format conversion: 

Input File -> Demuxer (splits video/audio streams to their respective codecs) -> 
[Audio Codec (Decode) || Video codec (Decode)] -> [Audio codec (Encode)  || Video 
Codec (Encode)] -> Muxer -> Output file.

(Muxer is a common abbreviation for multiplexer). 

Note that it is possible to change container formats without decoding/reencoding 
stream formats, provided both the source container format and destination 
container format are compatible with the format/s of the stream/s. 

Rodney Baker VK5ZTV
rodney.baker at iinet.net.au
CCNA #CSCO12880208

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