C API for extractor plugins
Define a C extractor plugin API, along with some helpers
so extractors can still be implemented in C++ if desired.
Bug: 111407253
Test: build, boot, play some files
Change-Id: Iba947381441769d77929b4235cdb4a4cd5d4f606
diff --git a/include/media/MediaExtractorPluginHelper.h b/include/media/MediaExtractorPluginHelper.h
new file mode 100644
index 0000000..465f76a
--- /dev/null
+++ b/include/media/MediaExtractorPluginHelper.h
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MEDIA_EXTRACTOR_PLUGIN_HELPER_H_
+
+#define MEDIA_EXTRACTOR_PLUGIN_HELPER_H_
+
+#include <stdio.h>
+#include <vector>
+
+#include <utils/Errors.h>
+#include <utils/Log.h>
+#include <utils/RefBase.h>
+#include <media/MediaExtractorPluginApi.h>
+
+namespace android {
+
+class DataSourceBase;
+class MetaDataBase;
+struct MediaTrack;
+
+// extractor plugins can derive from this class which looks remarkably
+// like MediaExtractor and can be easily wrapped in the required C API
+class MediaExtractorPluginHelper
+{
+public:
+ virtual ~MediaExtractorPluginHelper() {}
+ virtual size_t countTracks() = 0;
+ virtual MediaTrack *getTrack(size_t index) = 0;
+
+ enum GetTrackMetaDataFlags {
+ kIncludeExtensiveMetaData = 1
+ };
+ virtual status_t getTrackMetaData(
+ MetaDataBase& meta,
+ size_t index, uint32_t flags = 0) = 0;
+
+ // Return container specific meta-data. The default implementation
+ // returns an empty metadata object.
+ virtual status_t getMetaData(MetaDataBase& meta) = 0;
+
+ enum Flags {
+ CAN_SEEK_BACKWARD = 1, // the "seek 10secs back button"
+ CAN_SEEK_FORWARD = 2, // the "seek 10secs forward button"
+ CAN_PAUSE = 4,
+ CAN_SEEK = 8, // the "seek bar"
+ };
+
+ // If subclasses do _not_ override this, the default is
+ // CAN_SEEK_BACKWARD | CAN_SEEK_FORWARD | CAN_SEEK | CAN_PAUSE
+ virtual uint32_t flags() const {
+ return CAN_SEEK_BACKWARD | CAN_SEEK_FORWARD | CAN_SEEK | CAN_PAUSE;
+ };
+
+ virtual status_t setMediaCas(const uint8_t* /*casToken*/, size_t /*size*/) {
+ return INVALID_OPERATION;
+ }
+
+ virtual const char * name() { return "<unspecified>"; }
+
+protected:
+ MediaExtractorPluginHelper() {}
+
+private:
+ MediaExtractorPluginHelper(const MediaExtractorPluginHelper &);
+ MediaExtractorPluginHelper &operator=(const MediaExtractorPluginHelper &);
+};
+
+inline CMediaExtractor *wrap(MediaExtractorPluginHelper *extractor) {
+ CMediaExtractor *wrapper = (CMediaExtractor*) malloc(sizeof(CMediaExtractor));
+ wrapper->data = extractor;
+ wrapper->free = [](void *data) -> void {
+ delete (MediaExtractorPluginHelper*)(data);
+ };
+ wrapper->countTracks = [](void *data) -> size_t {
+ return ((MediaExtractorPluginHelper*)data)->countTracks();
+ };
+ wrapper->getTrack = [](void *data, size_t index) -> MediaTrack* {
+ return ((MediaExtractorPluginHelper*)data)->getTrack(index);
+ };
+ wrapper->getTrackMetaData = [](
+ void *data,
+ MetaDataBase& meta,
+ size_t index, uint32_t flags) -> status_t {
+ return ((MediaExtractorPluginHelper*)data)->getTrackMetaData(meta, index, flags);
+ };
+ wrapper->getMetaData = [](
+ void *data,
+ MetaDataBase& meta) -> status_t {
+ return ((MediaExtractorPluginHelper*)data)->getMetaData(meta);
+ };
+ wrapper->flags = [](
+ void *data) -> uint32_t {
+ return ((MediaExtractorPluginHelper*)data)->flags();
+ };
+ wrapper->setMediaCas = [](
+ void *data, const uint8_t *casToken, size_t size) -> status_t {
+ return ((MediaExtractorPluginHelper*)data)->setMediaCas(casToken, size);
+ };
+ wrapper->name = [](
+ void *data) -> const char * {
+ return ((MediaExtractorPluginHelper*)data)->name();
+ };
+ return wrapper;
+}
+
+// helpers to create a media_uuid_t from a string literal
+
+// purposely not defined anywhere so that this will fail to link if
+// expressions below are not evaluated at compile time
+int invalid_uuid_string(const char *);
+
+template <typename T, size_t N>
+constexpr uint8_t _digitAt_(const T (&s)[N], const size_t n) {
+ return s[n] >= '0' && s[n] <= '9' ? s[n] - '0'
+ : s[n] >= 'a' && s[n] <= 'f' ? s[n] - 'a' + 10
+ : s[n] >= 'A' && s[n] <= 'F' ? s[n] - 'A' + 10
+ : invalid_uuid_string("uuid: bad digits");
+}
+
+template <typename T, size_t N>
+constexpr uint8_t _hexByteAt_(const T (&s)[N], size_t n) {
+ return (_digitAt_(s, n) << 4) + _digitAt_(s, n + 1);
+}
+
+constexpr bool _assertIsDash_(char c) {
+ return c == '-' ? true : invalid_uuid_string("Wrong format");
+}
+
+template <size_t N>
+constexpr media_uuid_t constUUID(const char (&s) [N]) {
+ static_assert(N == 37, "uuid: wrong length");
+ return
+ _assertIsDash_(s[8]),
+ _assertIsDash_(s[13]),
+ _assertIsDash_(s[18]),
+ _assertIsDash_(s[23]),
+ media_uuid_t {{
+ _hexByteAt_(s, 0),
+ _hexByteAt_(s, 2),
+ _hexByteAt_(s, 4),
+ _hexByteAt_(s, 6),
+ _hexByteAt_(s, 9),
+ _hexByteAt_(s, 11),
+ _hexByteAt_(s, 14),
+ _hexByteAt_(s, 16),
+ _hexByteAt_(s, 19),
+ _hexByteAt_(s, 21),
+ _hexByteAt_(s, 24),
+ _hexByteAt_(s, 26),
+ _hexByteAt_(s, 28),
+ _hexByteAt_(s, 30),
+ _hexByteAt_(s, 32),
+ _hexByteAt_(s, 34),
+ }};
+}
+// Convenience macro to create a media_uuid_t from a string literal, which should
+// be formatted as "12345678-1234-1234-1234-123456789abc", as generated by
+// e.g. https://www.uuidgenerator.net/ or the 'uuidgen' linux command.
+// Hex digits may be upper or lower case.
+//
+// The macro call is otherwise equivalent to specifying the structure directly
+// (e.g. UUID("7d613858-5837-4a38-84c5-332d1cddee27") is the same as
+// {{0x7d, 0x61, 0x38, 0x58, 0x58, 0x37, 0x4a, 0x38,
+// 0x84, 0xc5, 0x33, 0x2d, 0x1c, 0xdd, 0xee, 0x27}})
+
+#define UUID(str) []{ constexpr media_uuid_t uuid = constUUID(str); return uuid; }()
+
+} // namespace android
+
+#endif // MEDIA_EXTRACTOR_PLUGIN_HELPER_H_