内容表

1 描述

NUT is a low overhead generic container format. It stores audio, video, subtitle and user-defined streams in a simple, yet efficient, way.

It was created by a group of FFmpeg and MPlayer developers in 2003 and was finalized in 2008.

The official nut specification is at svn://svn.mplayerhq.hu/nut In case of any differences between this text and the official specification, the official specification shall prevail.

2 Modes

NUT has some variants signaled by using the flags field in its main header.

2.1 BROADCAST

The BROADCAST variant provides a secondary time reference to facilitate detecting endpoint latency and network delays. It assumes all the endpoint clocks are synchronized. To be used in real-time scenarios.

2.2 PIPE

The PIPE variant assumes NUT is used as non-seekable intermediate container, by not using syncpoint removes unneeded overhead and reduces the overall memory usage.

3 Container-specific codec tags

3.1 Generic raw YUVA formats

Since many exotic planar YUVA pixel formats are not considered by the AVI/QuickTime FourCC lists, the following scheme is adopted for representing them.

The first two bytes can contain the values: Y1 = only Y Y2 = Y+A Y3 = YUV Y4 = YUVA

The third byte represents the width and height chroma subsampling values for the UV planes, that is the amount to shift the luma width/height right to find the chroma width/height.

The fourth byte is the number of bits used (8, 16, ...).

If the order of bytes is inverted, that means that each component has to be read big-endian.

3.2 Raw Audio

<type> is S for signed integer, U for unsigned integer, F for IEEE float <interleaving> is D for default, P is for planar. <bits> is 8/16/24/32

PFD[32]   would for example be signed 32 bit little-endian IEEE float
						

3.3 Subtitles

3.4 Raw Data

3.5 Codecs