TA的每日心情 | 奋斗 2020-5-6 08:48 |
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签到天数: 140 天 [LV.7]常住居民III
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我一直疑问为什么有些视频解码时显示格式是:H264,大部分又是:AVC1
) C, N) Y: O! V: Z. B( y0 o- ~我在搜索编程资料时在微软的msdn上发现的:0 c! y7 h4 A+ |+ F( Z; \
原文:http://msdn.microsoft.com/en-us/library/dd757808(v=vs.85).aspx
1 B+ y1 t) y, u& T! z2 E FOURCC:AVC1 描述:H.264 bitstream without start codes." O3 S; c' S j' }& ~
FOURCC:H264 描述:H.264 bitstream with start codes.
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H.264 Bitstream with Start Codes
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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.! L7 g. i/ [6 S" A6 O
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.
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H.264 Bitstream Without Start Codes6 g) |" E) B) \) j5 e" M( R1 P
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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.
" h# y8 w. V$ }" P% L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。* ]' a6 g$ p( q
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。* z, u9 H3 q- S6 W: E; V
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