Question

我找不到my previous question的解决方案，所以我决定一步一步地尝试。

我现在要做的是将RTP / H264流存储为文件。

到目前为止我发现的内容如下：

（首先我的RTP / H264是FU-A的形式）

| RTP HEADER 12bytes long | FU INDICATOR 1byte | FU HEADER 1byte | FU payload |

正如我理解RFC 6184文档，我正在启动一个NAL，其数据包在FU Header的第一位具有'1'，并在第一位附加后续数据包，直到最后一个数据包为止FU Header的第二位为'1'。

我认为在FU-A打包之前如何获得完整的NAL以及我发现的是我需要将'起始位'（0x00000001）放在每个完整NAL的前面。

但到目前为止还没有运气。以下是日志

的一部分

 ========= the new NAL is as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
 ========= adding the next NAL as 716
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
 ========= a NAL is summed up as 4866
 ========= the new NAL is as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= adding the next NAL as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= adding the next NAL as 139
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
 ========= a NAL is summed up as 7061
 ========= the new NAL is as 1377
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]41/1000001 [5]E4/11100100 [6]40/1000000 [7]1A/11010 ...
 ========= a NAL is summed up as 1369
 ========= the new NAL is as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E6/11100110 [7]60/1100000 ...
 ========= adding the next NAL as 94
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E6/11100110 [7]60/1100000 ...
 ========= a NAL is summed up as 1472
 ========= the new NAL is as 447
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]41/1000001 [5]E8/11101000 [6]80/10000000 [7]16/10110 ...
 ========= a NAL is summed up as 439
 ========= the new NAL is as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EA/11101010 [7]A0/10100000  ...
 ========= adding the next NAL as 1174
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EA/11101010 [7]A0/10100000 ...
 ========= a NAL is summed up as 2552
 ========= the new NAL is as 1400
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EC/11101100 [7]C0/11000000 ...
 ========= adding the next NAL as 1364
 [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EC/11101100 [7]C0/11000000 ...
 ========= a NAL is summed up as 2742
 ========= the new NAL is as 1400
 ...

我的问题是，

如果我可以通过FU-A从碎片包中获取完整的NAL，我该如何将其作为能够由VLC或其他播放器运行的文件？
如果我必须保留FU指示符和FU标题，我仍然感到困惑。有人说我只需要把它们拿到第一个数据包（从FU标题的'1'开始）

任何建议都会非常感激。

感谢。

Answer 1

FU，STAP和MTAP NAL单元仅针对RTP分组化，因为它们旨在促进网络传输。换句话说，不要指望正确解析它们的解码器。最终，您需要像FU数据包一样重新组合NAL单元，或者在STAP / MTAP的情况下将它们分解为多个NAL单元。

一旦你有一个NAL单元（这包括PPS，SPS，SEI，切片分区和1-23范围内的所有其他类型），那么你可以写入磁盘以及每个'0001'开始代码H.264附件B.

将H.264附件B流放入MPEG-4等容器中可以使用各种命令行工具（我很确定ffmpeg可以做到这一点）。

Answer 2

一种选择是将数据复制为文件格式，如mp4或avi，以便能够使用VLC播放。 AFAIR avi不适合H.264（不记得手头的原因）。有libmp4等免费库，如果您使用DirectShow Geraint's mp4mux在Windows上，则可以使用。

另一种选择是使用ffmpeg将.264文件转换为mp4

ffmpeg -i test.264 test.mp4

这假定.264文件包含由起始代码分隔的NAL单元。
来自RFC6184

FU有效载荷由分段的有效载荷的片段组成 NAL单元使得如果碎片单元的有效载荷连续 FU按顺序连接，即分段NAL的有效负载单位可以重建。分段的NAL单元类型八位字节 NAL单元不包含在碎片单元有效载荷中，而是NAL单位类型八位字节的信息分段的NAL单元在FU的F和NRI字段中传送碎片单元的指示符八位字节和类型字段 FU标题。 FU有效载荷可以具有任意数量的八位字节和MAY 是空的。

如果采用1中概述的第二种方法，则需要在将原始NAL单元写入.264文件之前重建原始NAL单元。

如何将RTP / H264流写为文件

2 个答案: