rtc源支持丢264 b帧操作

mtdxc · Jan 1, 2025 · f28fdf5 · f28fdf5
1 parent 4ddb88f
commit f28fdf5
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Showing 5 changed files with 79 additions and 1 deletion.
diff --git a/ext-codec/H264.cpp b/ext-codec/H264.cpp
@@ -26,6 +26,58 @@ using namespace std;
 using namespace toolkit;
 
 namespace mediakit {
+/* Helpers to decode Exp-Golomb */
+static uint32_t h264_eg_getbit(uint8_t *base, uint32_t offset) {
+    return ((*(base + (offset >> 0x3))) >> (0x7 - (offset & 0x7))) & 0x1;
+}
+
+static uint32_t h264_eg_decode(uint8_t *base, uint32_t *offset) {
+    uint32_t zeros = 0;
+    while (h264_eg_getbit(base, (*offset)++) == 0)
+        zeros++;
+    uint32_t res = 1 << zeros;
+    if (zeros > 0) {
+        int32_t i = 0;
+        for (i = zeros - 1; i >= 0; i--) {
+            res |= h264_eg_getbit(base, (*offset)++) << i;
+        }
+    }
+    return res - 1;
+}
+
+// @see https://blog.csdn.net/dittychen/article/details/55509718
+int h264_frameType(uint8_t *buffer, int size) {
+    uint8_t nalTye = buffer[0] & 0x1F;
+    if (nalTye != 1 && nalTye != 5) {
+        return 0;
+    }
+    buffer++;
+    int frametype = 0;
+    uint32_t offset = 0;
+    /* i_first_mb  */
+    h264_eg_decode(buffer, &offset);
+    /* picture type */
+    int frame_type = h264_eg_decode(buffer, &offset);
+    switch(frame_type)
+    {
+    case 0: case 5: // P
+        frametype = FRAME_P;
+        break;
+    case 1: case 6: // B
+        frametype = FRAME_B;
+        break;
+    case 3: case 8: // SP
+        frametype = FRAME_P;
+        break;
+    case 2: case 7: // I
+        frametype = FRAME_I;
+        break;
+    case 4: case 9: // SI
+        frametype = FRAME_I;
+        break;
+    }
+    return frametype;
+}
 
 static bool getAVCInfo(const char *sps, size_t sps_len, int &iVideoWidth, int &iVideoHeight, float &iVideoFps) {
     if (sps_len < 4) {

diff --git a/ext-codec/H264.h b/ext-codec/H264.h
@@ -20,6 +20,8 @@ namespace mediakit{
 
 void splitH264(const char *ptr, size_t len, size_t prefix, const std::function<void(const char *, size_t, size_t)> &cb);
 size_t prefixSize(const char *ptr, size_t len);
+enum H264FrameTye { FRAME_I, FRAME_P, FRAME_B };
+int h264_frameType(uint8_t *data, int size);
 
 template<typename Parent>
 class H264FrameHelper : public Parent{
@@ -72,6 +74,13 @@ class H264FrameHelper : public Parent{
         // // In the case of multiple slices, first_mb_in_slice indicates the start of a frame
         return type >= NAL_B_P && type <= NAL_IDR && (nal_ptr[1] & 0x80);
     }
+
+    bool bframe() const {
+        auto nal_ptr = (uint8_t *)this->data() + this->prefixSize();
+        if (H264_TYPE(*nal_ptr) != NAL_B_P)
+            return false;
+        return FRAME_B == h264_frameType(nal_ptr, this->size() - this->prefixSize());
+    }
 };
 
 /**

diff --git a/webrtc/RtcMediaSource.h b/webrtc/RtcMediaSource.h
@@ -3,6 +3,8 @@
 
 #include "Rtsp/RtspMediaSourceMuxer.h"
 #include "Rtsp/RtspMediaSourceImp.h"
+#include "webrtc/WebRtcTransport.h"
+#include "ext-codec/H264.h"
 namespace mediakit {
 
 class RtcMediaSourceImp : public RtspMediaSourceImp {
@@ -51,7 +53,19 @@ class RtcMediaSourceMuxer : public RtspMediaSourceMuxer {
                 _trans->delDelegate(this);
         }
     }
-protected:
+
+    bool inputFrame(const Frame::Ptr &frame) override { 
+        // skip b-frame for webrtc
+        GET_CONFIG(int, dropBFrame, Rtc::kDrop264BFrame);
+        if (dropBFrame && frame->getCodecId() == CodecH264) {
+            if (FRAME_B == h264_frameType((uint8_t *)frame->data() + frame->prefixSize(), frame->size() - frame->prefixSize())) {
+                DebugL << "skipFrame " << frame->size() << " tsp:" << frame->pts() << "," << frame->dts();
+                return true;
+            }
+        }
+        return RtspMediaSourceMuxer::inputFrame(frame);
+    }
+    protected:
     Track::Ptr _trans;
 };
 

diff --git a/webrtc/WebRtcTransport.cpp b/webrtc/WebRtcTransport.cpp
@@ -64,6 +64,7 @@ const string kMinBitrate = RTC_FIELD "min_bitrate";
 // 数据通道设置  [AUTO-TRANSLATED:2dc48bc3]
 // Data channel setting
 const string kDataChannelEcho = RTC_FIELD "datachannel_echo";
+const string kDrop264BFrame = RTC_FIELD "drop_h264_bframe";
 
 static onceToken token([]() {
     mINI::Instance()[kTimeOutSec] = 15;
@@ -76,6 +77,7 @@ static onceToken token([]() {
     mINI::Instance()[kMaxBitrate] = 0;
     mINI::Instance()[kMinBitrate] = 0;
 
+    mINI::Instance()[kDrop264BFrame] = true;
     mINI::Instance()[kDataChannelEcho] = true;
 });
 

diff --git a/webrtc/WebRtcTransport.h b/webrtc/WebRtcTransport.h
@@ -34,6 +34,7 @@ namespace Rtc {
 extern const std::string kPort;
 extern const std::string kTcpPort;
 extern const std::string kTimeOutSec;
+extern const std::string kDrop264BFrame;
 }//namespace RTC
 
 class WebRtcInterface {