新增对mp2音视频编码格式的支持

ext-codec/MP2V.h

@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#ifndef ZLMEDIAKIT_MP2V_H
+#define ZLMEDIAKIT_MP2V_H
+
+#include "Extension/Frame.h"
+#include "Extension/Track.h"
+
+namespace mediakit {
+
+/**
+ * MPEG-2 Video 帧辅助类模板
+ * MPEG-2 Video frame helper class template
+ */
+template <typename Parent>
+class MP2VFrameHelper : public Parent {
+public:
+    using Ptr = std::shared_ptr<MP2VFrameHelper>;
+
+    template <typename... ARGS>
+    MP2VFrameHelper(ARGS &&...args)
+        : Parent(std::forward<ARGS>(args)...) {
+        this->_codec_id = CodecMP2V;
+    }
+
+    /**
+     * MPEG-2 视频起始码: 00 00 01 00 (picture_start_code)
+     * I帧判断：picture_coding_type == 1 (I-Picture)
+     * picture_coding_type 位于 picture header 的第 11-12 bit (从 temporal_reference 之后)
+     *
+     * MPEG-2 video start code: 00 00 01 00 (picture_start_code)
+     * I-frame detection: picture_coding_type == 1 (I-Picture)
+     */
+    bool keyFrame() const override {
+        auto data = (const uint8_t *)this->data() + this->prefixSize();
+        auto size = this->size() - this->prefixSize();
+        return isMP2VKeyFrame(data, size);
+    }
+
+    bool configFrame() const override { return false; }
+
+    static bool isMP2VKeyFrame(const uint8_t *data, size_t size) {
+        // 查找 picture start code (00 00 01 00)，然后检查 picture_coding_type
+        // Look for picture start code (00 00 01 00), then check picture_coding_type
+        for (size_t i = 0; i + 5 < size; ++i) {
+            if (data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01 && data[i + 3] == 0x00) {
+                // picture header: temporal_reference(10bits) + picture_coding_type(3bits)
+                // picture_coding_type: 001 = I, 010 = P, 011 = B
+                uint8_t picture_coding_type = (data[i + 5] >> 3) & 0x07;
+                return picture_coding_type == 1;
+            }
+        }
+        return false;
+    }
+};
+
+/// MPEG-2 Video 帧类
+using MP2VFrame = MP2VFrameHelper<FrameImp>;
+using MP2VFrameNoCacheAble = MP2VFrameHelper<FrameFromPtr>;
+
+/**
+ * MPEG-2 Video Track
+ */
+class MP2VTrack : public VideoTrackImp {
+public:
+    using Ptr = std::shared_ptr<MP2VTrack>;
+
+    MP2VTrack() : VideoTrackImp(CodecMP2V) {}
+
+    Track::Ptr clone() const override { return std::make_shared<MP2VTrack>(*this); }
+
+    bool inputFrame(const Frame::Ptr &frame) override;
+
+private:
+    Sdp::Ptr getSdp(uint8_t payload_type) const override;
+
+    /**
+     * 从 sequence header 中解析宽高和帧率
+     * Parse width, height and fps from sequence header
+     */
+    void parseSequenceHeader(const uint8_t *data, size_t size);
+
+private:
+    bool _seq_header_parsed = false;
+};
+
+} // namespace mediakit
+
+#endif // ZLMEDIAKIT_MP2V_H