feat: add support of codec plugin

ext-codec/G711Rtp.cpp

@@ -0,0 +1,48 @@
+#include "G711Rtp.h"
+
+namespace mediakit {
+
+G711RtpEncoder::G711RtpEncoder(CodecId codec, uint32_t channels){
+    _cache_frame = FrameImp::create();
+    _cache_frame->_codec_id = codec;
+    _channels = channels;
+}
+
+bool G711RtpEncoder::inputFrame(const Frame::Ptr &frame) {
+    auto dur = (_cache_frame->size() - _cache_frame->prefixSize()) / (8 * _channels);
+    auto next_pts = _cache_frame->pts() + dur;
+    if (next_pts == 0) {
+        _cache_frame->_pts = frame->pts();
+    } else {
+        if ((next_pts + 20) < frame->pts()) { // 有丢包超过20ms
+            _cache_frame->_pts = frame->pts() - dur;
+        }
+    }
+    _cache_frame->_buffer.append(frame->data() + frame->prefixSize(), frame->size() - frame->prefixSize());
+
+    auto stamp = _cache_frame->pts();
+    auto ptr = _cache_frame->data() + _cache_frame->prefixSize();
+    auto len = _cache_frame->size() - _cache_frame->prefixSize();
+    auto remain_size = len;
+    auto max_size = 160 * _channels; // 20 ms per rtp
+    int n = 0;
+    bool mark = false;
+    while (remain_size >= max_size) {
+        size_t rtp_size;
+        if (remain_size >= max_size) {
+            rtp_size = max_size;
+        } else {
+            break;
+        }
+        n++;
+        stamp += 20;
+        RtpCodec::inputRtp(getRtpInfo().makeRtp(TrackAudio, ptr, rtp_size, mark, stamp), false);
+        ptr += rtp_size;
+        remain_size -= rtp_size;
+    }
+    _cache_frame->_buffer.erase(0, n * max_size);
+    _cache_frame->_pts += 20 * n;
+    return len > 0;
+}
+
+} // namespace mediakit