在c#中将Rtsp数据包转换为位图

Question

大家好，我已经在 c# https://github.com/ngraziano/SharpRTSP 中实现了 SharpRtsp 我正在接收 rtsp 数据包，它具有 h264 格式它在 H264Payload 类中有以下方法

private List<byte[]> Process_H264_RTP_Frame(List<byte[]> rtp_payloads)
        {
            Console.WriteLine("RTP Data comprised of " + rtp_payloads.Count + " rtp packets");

            List<byte[]> nal_units = new List<byte[]>(); // Stores the NAL units for a Video Frame. May be more than one NAL unit in a video frame.

            for (int payload_index = 0; payload_index < rtp_payloads.Count; payload_index++)
            {
                // Examine the first rtp_payload and the first byte (the NAL header)
                int nal_header_f_bit = (rtp_payloads[payload_index][0] >> 7) & 0x01;
                int nal_header_nri = (rtp_payloads[payload_index][0] >> 5) & 0x03;
                int nal_header_type = (rtp_payloads[payload_index][0] >> 0) & 0x1F;

                // If the Nal Header Type is in the range 1..23 this is a normal NAL (not fragmented)
                // So write the NAL to the file
                if (nal_header_type >= 1 && nal_header_type <= 23)
                {
                    Console.WriteLine("Normal NAL");
                    norm++;
                    nal_units.Add(rtp_payloads[payload_index]);
                }
                // There are 4 types of Aggregation Packet (split over RTP payloads)
                else if (nal_header_type == 24)
                {
                    Console.WriteLine("Agg STAP-A");
                    stap_a++;

                    // RTP packet contains multiple NALs, each with a 16 bit header
                    //   Read 16 byte size
                    //   Read NAL
                    try
                    {
                        int ptr = 1; // start after the nal_header_type which was '24'
                        // if we have at least 2 more bytes (the 16 bit size) then consume more data
                        while (ptr + 2 < (rtp_payloads[payload_index].Length - 1))
                        {
                            int size = (rtp_payloads[payload_index][ptr] << 8) + (rtp_payloads[payload_index][ptr + 1] << 0);
                            ptr = ptr + 2;
                            byte[] nal = new byte[size];
                            System.Array.Copy(rtp_payloads[payload_index], ptr, nal, 0, size); // copy the NAL
                            nal_units.Add(nal); // Add to list of NALs for this RTP frame. Start Codes like 00 00 00 01 get added later
                            ptr = ptr + size;
                        }
                    }
                    catch
                    {
                        // do nothing
                    }
                }
                else if (nal_header_type == 25)
                {
                    Console.WriteLine("Agg STAP-B not supported");
                    stap_b++;
                }
                else if (nal_header_type == 26)
                {
                    Console.WriteLine("Agg MTAP16 not supported");
                    mtap16++;
                }
                else if (nal_header_type == 27)
                {
                    Console.WriteLine("Agg MTAP24 not supported");
                    mtap24++;
                }
                else if (nal_header_type == 28)
                {
                    Console.WriteLine("Frag FU-A");
                    fu_a++;

                    // Parse Fragmentation Unit Header
                    int fu_header_s = (rtp_payloads[payload_index][1] >> 7) & 0x01;  // start marker
                    int fu_header_e = (rtp_payloads[payload_index][1] >> 6) & 0x01;  // end marker
                    int fu_header_r = (rtp_payloads[payload_index][1] >> 5) & 0x01;  // reserved. should be 0
                    int fu_header_type = (rtp_payloads[payload_index][1] >> 0) & 0x1F; // Original NAL unit header

                    Console.WriteLine("Frag FU-A s=" + fu_header_s + "e=" + fu_header_e);

                    // Check Start and End flags
                    if (fu_header_s == 1 && fu_header_e == 0)
                    {
                        // Start of Fragment.
                        // Initiise the fragmented_nal byte array
                        // Build the NAL header with the original F and NRI flags but use the the Type field from the fu_header_type
                        byte reconstructed_nal_type = (byte)((nal_header_f_bit << 7) + (nal_header_nri << 5) + fu_header_type);

                        // Empty the stream
                        fragmented_nal.SetLength(0);

                        // Add reconstructed_nal_type byte to the memory stream
                        fragmented_nal.WriteByte(reconstructed_nal_type);

                        // copy the rest of the RTP payload to the memory stream
                        fragmented_nal.Write(rtp_payloads[payload_index], 2, rtp_payloads[payload_index].Length - 2);
                    }

                    if (fu_header_s == 0 && fu_header_e == 0)
                    {
                        // Middle part of Fragment
                        // Append this payload to the fragmented_nal
                        // Data starts after the NAL Unit Type byte and the FU Header byte
                        fragmented_nal.Write(rtp_payloads[payload_index], 2, rtp_payloads[payload_index].Length - 2);
                    }

                    if (fu_header_s == 0 && fu_header_e == 1)
                    {
                        // End part of Fragment
                        // Append this payload to the fragmented_nal
                        // Data starts after the NAL Unit Type byte and the FU Header byte
                        fragmented_nal.Write(rtp_payloads[payload_index], 2, rtp_payloads[payload_index].Length - 2);

                        // Add the NAL to the array of NAL units
                        nal_units.Add(fragmented_nal.ToArray());
                    }
                }

                else if (nal_header_type == 29)
                {
                    Console.WriteLine("Frag FU-B not supported");
                    fu_b++;
                }
                else
                {
                    Console.WriteLine("Unknown NAL header " + nal_header_type + " not supported");
                }

            }

            // Output some statistics
            Console.WriteLine("Norm=" + norm + " ST-A=" + stap_a + " ST-B=" + stap_b + " M16=" + mtap16 + " M24=" + mtap24 + " FU-A=" + fu_a + " FU-B=" + fu_b);

            // Output all the NALs that form one RTP Frame (one frame of video)
            return nal_units;

        }


    }

我已经阅读并完成了阅读，但我还没有找到任何方法将 H264 帧转换为位图我只想将它保存为位图有任何机构可以帮助我将这些数据转换为位图吗？

Answer 1

该函数的末尾返回 H264 格式的数据

        // Output all the NALs that form one RTP Frame (one frame of video)
        return nal_units;

要获得位图，您需要将 H264 数据传递到视频解压缩器。如果您不熟悉数字视频，请考虑 .ZIP 或 .RAR 或 .7Z 文件。 如果没有合适的软件将压缩数据转换回可用格式，您将无法读取这些文件的内容。 这同样适用于视频。 H264 是一种压缩数据格式。 您需要使用 H264 解压缩编解码器将 nal_units 赋予位图（或另一种称为 YUV 的视频格式）。

有些人使用 ffmpeg 进行此解压。其他人将 H264 数据传递到操作系统 API（如 Mac 上的 VideoToolbox 或 Android 上的 MediaCodec 或 Windows 支持的任何东西）。

但是您需要这些额外的步骤。