[英]How to understand header of H.265
Could someone explain me the difference between the H.264 header and H.265 header?有人可以解释一下 H.264 header 和 H.265 header 之间的区别吗? I just need to parse H265 header but I have difficult to find proper reference.
我只需要解析 H265 header 但我很难找到合适的参考。
I did a first version of the parser.我做了第一个版本的解析器。 I need to retrieve the pic_width_in_luma_samples, pic_height_in_luma_samples, and the aspectRatioH, aspectRatioV.
我需要检索 pic_width_in_luma_samples、pic_height_in_luma_samples 和 aspectRatioH、aspectRatioV。
my code is something like:我的代码是这样的:
while (buf->Size > 0)
{
//forbidden bit
flushbits(buf, 1);
int nNALType = showbits(buf, 6);
if (nNALType == NAL_TYPE_SPS)
{
// flushbits until I retrieve desired parameter
flushbits(buf, 4); // sps_video_parameter_set_id
}
else
{
// align bits
buf->Size -= buf->BitsLeft & 0x7;
}
}
this is the correct way to do?这是正确的做法吗? There is a method where I can skip bits until I find a "start sequence" that indicates my desired SPS NAL TYPE?
有一种方法可以让我跳过位,直到找到指示我想要的 SPS NAL 类型的“开始序列”?
The syntax of H.264 and H.265 is relative similar. H.264 和 H.265 的语法相对相似。
Both have parameter sets (PPS, SPS) you find the details in the specification below.两者都有参数集(PPS、SPS),您可以在下面的规范中找到详细信息。 For H.265 - page 33 section 7.3 describes the video parameters sets in detail.
对于 H.265 - 第 33 页,第 7.3 节详细描述了视频参数集。 The specification is done in 'C' like pseudocode so relatively easy to translate the specification into compiling code.
规范是用类似伪代码的“C”语言完成的,因此将规范翻译成编译代码相对容易。
You can always look at some existing code - for example:您可以随时查看一些现有代码 - 例如:
https://github.com/GStreamer/gstreamer/blob/main/subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/gsth265parser.c https://github.com/GStreamer/gstreamer/blob/main/subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/gsth265parser.c
The H.264 (AVC) specification is here: H.264 (AVC) 规范在这里:
https://www.itu.int/rec/T-REC-H.264-202108-I/en https://www.itu.int/rec/T-REC-H.264-202108-I/en
The H.265 (HEVC) specification is here: H.265 (HEVC) 规范在这里:
https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-H.265-201802-S!!PDF-E&type=items https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-H.265-201802-S!!PDF-E&type=items
follow those step to parse H265按照这些步骤解析 H265
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