Add mp3_plugin, support rtsp with mp3 (#4048)

增加mp3_plugin, 解决rtmp推流转rtsp无法播放问题
ref: https://datatracker.ietf.org/doc/html/rfc2250#section-3.5

ext-codec/MP3.cpp

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2016-present The ZLMediaKit project authors. All Rights Reserved.
+ *
+ * This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
+ *
+ * Use of this source code is governed by MIT-like license that can be found in the
+ * LICENSE file in the root of the source tree. All contributing project authors
+ * may be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "MP3.h"
+#include "MP3Rtp.h"
+#include "Extension/Factory.h"
+#include "Extension/CommonRtp.h"
+#include "Extension/CommonRtmp.h"
+
+using namespace std;
+using namespace toolkit;
+
+namespace mediakit {
+
+Sdp::Ptr MP3Track::getSdp(uint8_t payload_type) const {
+    return std::make_shared<DefaultSdp>(payload_type, *this);
+}
+
+Track::Ptr MP3Track::clone() const {
+    return std::make_shared<MP3Track>(*this);
+}
+
+namespace {
+
+CodecId getCodec() {
+    return CodecMP3;
+}
+
+Track::Ptr getTrackByCodecId(int sample_rate, int channels, int sample_bit) {
+    return std::make_shared<MP3Track>(sample_rate, channels);
+}
+
+Track::Ptr getTrackBySdp(const SdpTrack::Ptr &track) {
+    return std::make_shared<MP3Track>(track->_samplerate, track->_channel);
+}
+
+RtpCodec::Ptr getRtpEncoderByCodecId(uint8_t pt) {
+    return std::make_shared<MP3RtpEncoder>();
+}
+
+RtpCodec::Ptr getRtpDecoderByCodecId() {
+    return std::make_shared<MP3RtpDecoder>();
+}
+
+RtmpCodec::Ptr getRtmpEncoderByTrack(const Track::Ptr &track) {
+    return std::make_shared<CommonRtmpEncoder>(track);
+}
+
+RtmpCodec::Ptr getRtmpDecoderByTrack(const Track::Ptr &track) {
+    return std::make_shared<CommonRtmpDecoder>(track);
+}
+
+Frame::Ptr getFrameFromPtr(const char *data, size_t bytes, uint64_t dts, uint64_t pts) {
+    return std::make_shared<FrameFromPtr>(CodecMP3, (char *)data, bytes, dts, pts);
+}
+
+} // namespace
+
+CodecPlugin mp3_plugin = { getCodec,
+                           getTrackByCodecId,
+                           getTrackBySdp,
+                           getRtpEncoderByCodecId,
+                           getRtpDecoderByCodecId,
+                           getRtmpEncoderByTrack,
+                           getRtmpDecoderByTrack,
+                           getFrameFromPtr };
+
+}//namespace mediakit
+
+