1 files changed, 318 insertions, 0 deletions
diff --git a/externals/oboe/samples/RhythmGame/src/main/cpp/audio/FFMpegExtractor.cpp b/externals/oboe/samples/RhythmGame/src/main/cpp/audio/FFMpegExtractor.cpp
new file mode 100644
index 0000000000..97d212f369
--- /dev/null
+++ b/externals/oboe/samples/RhythmGame/src/main/cpp/audio/FFMpegExtractor.cpp
@@ -0,0 +1,318 @@
+/*
+ * Copyright 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.
+ */
+
+#include <memory>
+#include <oboe/Definitions.h>
+#include "FFMpegExtractor.h"
+#include "utils/logging.h"
+
+constexpr int kInternalBufferSize = 1152; // Use MP3 block size. https://wiki.hydrogenaud.io/index.php?title=MP3
+
+int read(void *opaque, uint8_t *buf, int buf_size) {
+
+    auto asset = (AAsset *) opaque;
+    int bytesRead = AAsset_read(asset, buf, (size_t)buf_size);
+    return bytesRead;
+}
+
+int64_t seek(void *opaque, int64_t offset, int whence){
+
+    auto asset = (AAsset*)opaque;
+
+    // See https://www.ffmpeg.org/doxygen/3.0/avio_8h.html#a427ff2a881637b47ee7d7f9e368be63f
+    if (whence == AVSEEK_SIZE) return AAsset_getLength(asset);
+    if (AAsset_seek(asset, offset, whence) == -1){
+        return -1;
+    } else {
+        return 0;
+    }
+}
+
+bool FFMpegExtractor::createAVIOContext(AAsset *asset, uint8_t *buffer, uint32_t bufferSize,
+                                        AVIOContext **avioContext) {
+
+    constexpr int isBufferWriteable = 0;
+
+    *avioContext = avio_alloc_context(
+            buffer, // internal buffer for FFmpeg to use
+            bufferSize, // For optimal decoding speed this should be the protocol block size
+            isBufferWriteable,
+            asset, // Will be passed to our callback functions as a (void *)
+            read, // Read callback function
+            nullptr, // Write callback function (not used)
+            seek); // Seek callback function
+
+    if (*avioContext == nullptr){
+        LOGE("Failed to create AVIO context");
+        return false;
+    } else {
+        return true;
+    }
+}
+
+bool
+FFMpegExtractor::createAVFormatContext(AVIOContext *avioContext, AVFormatContext **avFormatContext) {
+
+    *avFormatContext = avformat_alloc_context();
+    (*avFormatContext)->pb = avioContext;
+
+    if (*avFormatContext == nullptr){
+        LOGE("Failed to create AVFormatContext");
+        return false;
+    } else {
+        return true;
+    }
+}
+
+bool FFMpegExtractor::openAVFormatContext(AVFormatContext *avFormatContext) {
+
+    int result = avformat_open_input(&avFormatContext,
+                                     "", /* URL is left empty because we're providing our own I/O */
+                                     nullptr /* AVInputFormat *fmt */,
+                                     nullptr /* AVDictionary **options */
+    );
+
+    if (result == 0) {
+        return true;
+    } else {
+        LOGE("Failed to open file. Error code %s", av_err2str(result));
+        return false;
+    }
+}
+
+bool FFMpegExtractor::getStreamInfo(AVFormatContext *avFormatContext) {
+
+    int result = avformat_find_stream_info(avFormatContext, nullptr);
+    if (result == 0 ){
+        return true;
+    } else {
+        LOGE("Failed to find stream info. Error code %s", av_err2str(result));
+        return false;
+    }
+}
+
+AVStream *FFMpegExtractor::getBestAudioStream(AVFormatContext *avFormatContext) {
+    
+    int streamIndex = av_find_best_stream(avFormatContext, AVMEDIA_TYPE_AUDIO, -1, -1, nullptr, 0);
+
+    if (streamIndex < 0){
+        LOGE("Could not find stream");
+        return nullptr;
+    } else {
+        return avFormatContext->streams[streamIndex];
+    }
+}
+
+int64_t FFMpegExtractor::decode(
+        AAsset *asset,
+        uint8_t *targetData,
+        AudioProperties targetProperties) {
+
+    LOGI("Decoder: FFMpeg");
+
+    int returnValue = -1; // -1 indicates error
+
+    // Create a buffer for FFmpeg to use for decoding (freed in the custom deleter below)
+    auto buffer = reinterpret_cast<uint8_t*>(av_malloc(kInternalBufferSize));
+
+    // Create an AVIOContext with a custom deleter
+    std::unique_ptr<AVIOContext, void(*)(AVIOContext *)> ioContext {
+            nullptr,
+            [](AVIOContext *c) {
+                av_free(c->buffer);
+                avio_context_free(&c);
+            }
+    };
+    {
+        AVIOContext *tmp = nullptr;
+        if (!createAVIOContext(asset, buffer, kInternalBufferSize, &tmp)){
+            LOGE("Could not create an AVIOContext");
+            return returnValue;
+        }
+        ioContext.reset(tmp);
+    }
+
+    // Create an AVFormatContext using the avformat_free_context as the deleter function
+    std::unique_ptr<AVFormatContext, decltype(&avformat_free_context)> formatContext {
+            nullptr,
+            &avformat_free_context
+    };
+    {
+        AVFormatContext *tmp;
+        if (!createAVFormatContext(ioContext.get(), &tmp)) return returnValue;
+        formatContext.reset(tmp);
+    }
+
+    if (!openAVFormatContext(formatContext.get())) return returnValue;
+
+    if (!getStreamInfo(formatContext.get())) return returnValue;
+
+    // Obtain the best audio stream to decode
+    AVStream *stream = getBestAudioStream(formatContext.get());
+    if (stream == nullptr || stream->codecpar == nullptr){
+        LOGE("Could not find a suitable audio stream to decode");
+        return returnValue;
+    }
+
+    printCodecParameters(stream->codecpar);
+
+    // Find the codec to decode this stream
+    AVCodec *codec = avcodec_find_decoder(stream->codecpar->codec_id);
+    if (!codec){
+        LOGE("Could not find codec with ID: %d", stream->codecpar->codec_id);
+        return returnValue;
+    }
+
+    // Create the codec context, specifying the deleter function
+    std::unique_ptr<AVCodecContext, void(*)(AVCodecContext *)> codecContext {
+            nullptr,
+            [](AVCodecContext *c) { avcodec_free_context(&c); }
+    };
+    {
+        AVCodecContext *tmp = avcodec_alloc_context3(codec);
+        if (!tmp){
+            LOGE("Failed to allocate codec context");
+            return returnValue;
+        }
+        codecContext.reset(tmp);
+    }
+
+    // Copy the codec parameters into the context
+    if (avcodec_parameters_to_context(codecContext.get(), stream->codecpar) < 0){
+        LOGE("Failed to copy codec parameters to codec context");
+        return returnValue;
+    }
+
+    // Open the codec
+    if (avcodec_open2(codecContext.get(), codec, nullptr) < 0){
+        LOGE("Could not open codec");
+        return returnValue;
+    }
+
+    // prepare resampler
+    int32_t outChannelLayout = (1 << targetProperties.channelCount) - 1;
+    LOGD("Channel layout %d", outChannelLayout);
+
+    SwrContext *swr = swr_alloc();
+    av_opt_set_int(swr, "in_channel_count", stream->codecpar->channels, 0);
+    av_opt_set_int(swr, "out_channel_count", targetProperties.channelCount, 0);
+    av_opt_set_int(swr, "in_channel_layout", stream->codecpar->channel_layout, 0);
+    av_opt_set_int(swr, "out_channel_layout", outChannelLayout, 0);
+    av_opt_set_int(swr, "in_sample_rate", stream->codecpar->sample_rate, 0);
+    av_opt_set_int(swr, "out_sample_rate", targetProperties.sampleRate, 0);
+    av_opt_set_int(swr, "in_sample_fmt", stream->codecpar->format, 0);
+    av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_FLT, 0);
+    av_opt_set_int(swr, "force_resampling", 1, 0);
+
+    // Check that resampler has been inited
+    int result = swr_init(swr);
+    if (result != 0){
+        LOGE("swr_init failed. Error: %s", av_err2str(result));
+        return returnValue;
+    };
+    if (!swr_is_initialized(swr)) {
+        LOGE("swr_is_initialized is false\n");
+        return returnValue;
+    }
+
+    // Prepare to read data
+    int bytesWritten = 0;
+    AVPacket avPacket; // Stores compressed audio data
+    av_init_packet(&avPacket);
+    AVFrame *decodedFrame = av_frame_alloc(); // Stores raw audio data
+    int bytesPerSample = av_get_bytes_per_sample((AVSampleFormat)stream->codecpar->format);
+
+    LOGD("Bytes per sample %d", bytesPerSample);
+
+    LOGD("DECODE START");
+
+    // While there is more data to read, read it into the avPacket
+    while (av_read_frame(formatContext.get(), &avPacket) == 0){
+
+        if (avPacket.stream_index == stream->index && avPacket.size > 0) {
+
+            // Pass our compressed data into the codec
+            result = avcodec_send_packet(codecContext.get(), &avPacket);
+            if (result != 0) {
+                LOGE("avcodec_send_packet error: %s", av_err2str(result));
+                goto cleanup;
+            }
+
+            // Retrieve our raw data from the codec
+            result = avcodec_receive_frame(codecContext.get(), decodedFrame);
+            if (result == AVERROR(EAGAIN)) {
+                // The codec needs more data before it can decode
+                LOGI("avcodec_receive_frame returned EAGAIN");
+                av_packet_unref(&avPacket);
+                continue;
+            } else if (result != 0) {
+                LOGE("avcodec_receive_frame error: %s", av_err2str(result));
+                goto cleanup;
+            }
+
+            // DO RESAMPLING
+            auto dst_nb_samples = (int32_t) av_rescale_rnd(
+                    swr_get_delay(swr, decodedFrame->sample_rate) + decodedFrame->nb_samples,
+                    targetProperties.sampleRate,
+                    decodedFrame->sample_rate,
+                    AV_ROUND_UP);
+
+            short *buffer1;
+            av_samples_alloc(
+                    (uint8_t **) &buffer1,
+                    nullptr,
+                    targetProperties.channelCount,
+                    dst_nb_samples,
+                    AV_SAMPLE_FMT_FLT,
+                    0);
+            int frame_count = swr_convert(
+                    swr,
+                    (uint8_t **) &buffer1,
+                    dst_nb_samples,
+                    (const uint8_t **) decodedFrame->data,
+                    decodedFrame->nb_samples);
+
+            int64_t bytesToWrite = frame_count * sizeof(float) * targetProperties.channelCount;
+            memcpy(targetData + bytesWritten, buffer1, (size_t)bytesToWrite);
+            bytesWritten += bytesToWrite;
+            av_freep(&buffer1);
+
+            av_packet_unref(&avPacket);
+        }
+    }
+
+    av_frame_free(&decodedFrame);
+    LOGD("DECODE END");
+
+    returnValue = bytesWritten;
+
+    cleanup:
+    return returnValue;
+}
+
+void FFMpegExtractor::printCodecParameters(AVCodecParameters *params) {
+
+    LOGD("Stream properties");
+    LOGD("Channels: %d", params->channels);
+    LOGD("Channel layout: %" PRId64, params->channel_layout);
+    LOGD("Sample rate: %d", params->sample_rate);
+    LOGD("Format: %s", av_get_sample_fmt_name((AVSampleFormat)params->format));
+    LOGD("Frame size: %d", params->frame_size);
+}
+
+
+
+