H264/AVC视频解码时AVC1和H264的区别

AVC1与H264的区别

http://blog.csdn.net/qiuchangyong/article/details/6660253

H.264 Video Types

The following media subtypes are defined for H.264 video.
Subtype    FOURCC    Description
MEDIASUBTYPE_AVC1    'AVC1'    H.264 bitstream without start codes.
MEDIASUBTYPE_H264    'H264'    H.264 bitstream with start codes.
MEDIASUBTYPE_h264    'h264'    Equivalent to MEDIASUBTYPE_H264, with a different FOURCC.
MEDIASUBTYPE_X264    'X264'    Equivalent to MEDIASUBTYPE_H264, with a different FOURCC.
MEDIASUBTYPE_x264    'x264'    Equivalent to MEDIASUBTYPE_H264, with a different FOURCC.

The main difference between these media types is the presence of startcodes in the bitstream. If the subtype is MEDIASUBTYPE_AVC1, thebitstream does not contain start codes.

H264/AVC视频解码时AVC1和H264的区别

http://blog.csdn.net/ameyume/article/details/7542979

FOURCC:AVC1   描述:H.264 bitstream without start codes.
FOURCC:H264   描述:H.264 bitstream with start codes.

H.264 Bitstream with Start Codes

H.264 bitstreams that are transmitted over the air, or contained in MPEG-2 program or transport streams, or recorded on HD-DVD, are formatted as described in Annex B of ITU-T Rec. H.264. According to this specification, the bitstream consists of a sequence of network abstraction layer units (NALUs), each of which is prefixed with a start code equal to 0x000001 or 0x00000001.
这段话的大致意思是：带有开始码的H.264视频一般是用于无线发射、有线广播或者HD-DVD中的。这些数据流的开始都有一个开始码：0x000001 或者 0x00000001.

H.264 Bitstream Without Start Codes

The MP4 container format stores H.264 data without start codes. Instead, each NALU is prefixed by a length field, which gives the length of the NALU in bytes. The size of the length field can vary, but is typically 1, 2, or 4 bytes.
这段话的大致意思是：没有开始码的H.264视频主要是存储在MP4格式的文件中的。它的数据流的开始是1、2或者4个字节表示长度数据。

原文中的"NALU"简单说是H.264格式中的最基本的单元，是一个数据包。