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niboshiniboshi
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MediaDecoder.*
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‎MediaDecoder.cpp

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#include "MediaDecoder.hpp"
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void
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MediaDecoder::initFfmpeg()
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{
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//av_log_set_callback(NULL);
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avcodec_register_all();
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av_register_all();
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}
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void
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MediaDecoder::outputMessage(int level, const char* format, ...)
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{
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va_list vl;
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va_start(vl, format);
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vprintf(format, vl);
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printf("\n");
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va_end(vl);
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}
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MediaDecoder::MediaDecoder()
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: mFormatContext(NULL),
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mSwsContext(NULL),
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mFirstVideoStreamIndex(-1),
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mScaleWidth(-1), mScaleHeight(-1), mScaleStride(-1), mScalePixelFormat(PIX_FMT_NONE)
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{
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mFrame = avcodec_alloc_frame();
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}
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MediaDecoder::~MediaDecoder()
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{
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if (mSwsContext) {
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sws_freeContext(mSwsContext);
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mSwsContext = NULL;
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}
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if (mFrame) {
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av_free(mFrame);
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mFrame = NULL;
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}
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if (mFormatContext) {
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av_close_input_file(mFormatContext);
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mFormatContext = NULL;
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}
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}
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int
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MediaDecoder::openFile(const char* filename)
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{
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int intRet;
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// open the input file.
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if (0 > (intRet = av_open_input_file(&mFormatContext, filename, NULL, 0, NULL))) {
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this->outputMessage(0, "Could not open input file: ret=%d file=%s", intRet, filename);
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return intRet;
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}
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if (0 > (intRet = av_find_stream_info(mFormatContext))) {
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this->outputMessage(0, "av_find_stream_info() failed: ret=%d", intRet);
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return intRet;
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}
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int streamCount = mFormatContext->nb_streams;
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// prepare the streams.
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for (int i = 0; i < streamCount; ++i) {
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if (0 > (intRet = this->prepareStream(i))) {
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this->outputMessage(0, "prepareStream() failed: ret=%d", intRet);
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return intRet;
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}
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if (mFirstVideoStreamIndex == -1 && mFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
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mFirstVideoStreamIndex = i;
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}
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}
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if (mFirstVideoStreamIndex != -1) {
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AVCodecContext* codecContext = mFormatContext->streams[mFirstVideoStreamIndex]->codec;
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this->setScaleParameters(codecContext->width, codecContext->height, PIX_FMT_RGB32, Stride_4bytes);
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}
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return 0;
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}
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static int
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getSmallestPowerOfTwo(int n) {
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int f = 0;
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int c = 0;
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while (n > 1) {
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f |= (n & 1);
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n >>= 1;
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c++;
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}
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if (f) { c++; }
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return n << c;
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}
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int
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MediaDecoder::setScaleParameters(int width, int height, PixelFormat pixelFormat, StrideMode strideMode)
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{
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AVCodecContext* codecContext = this->getVideoCodec();
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if (codecContext == NULL) {
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this->outputMessage(0, "No video stream found. Cannot set scale parameters.");
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return -1;
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}
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mSwsContext = sws_getCachedContext(
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mSwsContext,
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codecContext->width,
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codecContext->height,
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codecContext->pix_fmt,
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width,
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height,
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pixelFormat,
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// SWS_LANCZOS,
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// SWS_BILINEAR,
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SWS_FAST_BILINEAR,
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NULL, NULL, NULL);
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if (!mSwsContext) {
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this->outputMessage(0, "sws_getContext failed.");
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return -1;
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}
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// calc stride
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int tightLineSize = avpicture_get_size(pixelFormat, width, 1);
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int stride = -1;
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switch (strideMode) {
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case Stride_Tight:
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stride = tightLineSize;
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break;
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case Stride_PowerOfTwo:
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stride = getSmallestPowerOfTwo(tightLineSize);
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break;
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case Stride_4bytes:
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stride = ((tightLineSize + 3) >> 2) << 2;
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break;
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default:
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this->outputMessage(0, "Unknown stride mode: %d", strideMode);
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return -1;
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}
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mScaleStride = stride;
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mScaleWidth = width;
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mScaleHeight = height;
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mScalePixelFormat = pixelFormat;
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return 0;
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}
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int
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MediaDecoder::seek(double timestamp)
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{
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int intRet;
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int streamCount = this->getStreamCount();
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int failCount = 0;
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for (int i = 0; i < streamCount; ++i) {
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double timeBase = av_q2d(mFormatContext->streams[i]->time_base);
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int64_t ts = static_cast<int64_t>(timestamp / timeBase);
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intRet = av_seek_frame(mFormatContext, i, ts, 0);
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if (0 > intRet) {
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failCount ++;
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}
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}
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return failCount;
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}
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int
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MediaDecoder::seekToIndex(int streamIndex, int index) {
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AVStream* stream = this->getStream(streamIndex);
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if (!stream) { return -1; }
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AVIndexEntry* entries = stream->index_entries;
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if (!entries) { return -1; }
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if (0 < index || index <= stream->nb_index_entries) {
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return -1;
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}
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AVIndexEntry* entry = &entries[index];
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int ret = url_fseek(mFormatContext->pb, entry->pos, SEEK_SET);
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if (ret < 0) { return ret; }
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av_update_cur_dts(mFormatContext, stream, entry->timestamp);
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return 0;
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}
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int
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MediaDecoder::readPacket(AVPacket* packet)
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{
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int ret = av_read_frame(mFormatContext, packet);
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if (ret == AVERROR_EOF) { return ret; }
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if (ret < 0) {
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this->outputMessage(0, "av_read_frame() failed: %d", ret);
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}
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return ret;
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}
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double
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MediaDecoder::getVideoTimestamp(AVPacket* packet, AVFrame* frame)
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{
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AVStream* stream = mFormatContext->streams[packet->stream_index];
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int64_t pts = 0;
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if (frame->reordered_opaque != (signed)AV_NOPTS_VALUE) {
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pts = frame->reordered_opaque;
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} else if (packet->dts != (signed)AV_NOPTS_VALUE) {
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pts = packet->dts;
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}
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double timeBase = av_q2d(stream->time_base);
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return pts * timeBase;
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}
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int
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MediaDecoder::decodeVideoFrame(AVPacket* packet, AVFrame* outFrame, double* outTimestamp)
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{
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int intRet;
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int gotPicture;
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int streamIndex = packet->stream_index;
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AVCodecContext* codecContext = mFormatContext->streams[streamIndex]->codec;
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codecContext->reordered_opaque = packet->pts;
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intRet = avcodec_decode_video2(codecContext, outFrame, &gotPicture, packet);
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if (0 > intRet) { return intRet; }
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if (!gotPicture) { return 1; }
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if (outTimestamp) {
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*outTimestamp = this->getVideoTimestamp(packet, outFrame);
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}
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return 0;
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}
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int
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MediaDecoder::scaleVideoFrame(AVFrame* frame, uint8_t* buffer, int bufferSize)
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{
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int intRet;
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uint8_t* data[] = { (uint8_t*)buffer, NULL, NULL, NULL };
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int lineSize[] = { mScaleStride, 0, 0, 0 };
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if (bufferSize < this->getScaleBufferSize()) {
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this->outputMessage(0, "Insufficient buffer size (%d). %d is required.", bufferSize, this->getScaleBufferSize());
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return -1;
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}
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intRet = sws_scale(
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mSwsContext,
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frame->data, // src
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frame->linesize, // src stride
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0, // src slice Y
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mScaleHeight, // src slice H
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data, // dst
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lineSize // dst stride
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);
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return intRet;
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}
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int
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MediaDecoder::decodeVideo(AVPacket* packet, uint8_t* buffer, int bufferSize, double thresholdTimestamp, double* outTimestamp, int* outDataSize, bool* outSkipped)
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{
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int intRet;
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int result = 0;
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double timestamp;
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*outTimestamp = 0.0;
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*outDataSize = 0;
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*outSkipped = false;
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// Decode the next frame
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intRet = this->decodeVideoFrame(packet, mFrame, &timestamp);
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if (intRet != 0) {
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result = intRet;
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goto CLEANUP;
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}
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if (timestamp < thresholdTimestamp) {
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*outSkipped = true;
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result = 1;
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goto CLEANUP;
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}
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// scale and transform
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intRet = this->scaleVideoFrame(mFrame, buffer, bufferSize);
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if (intRet < 0) {
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result = intRet;
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goto CLEANUP;
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}
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*outTimestamp = timestamp;
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*outDataSize = mScaleHeight * mScaleStride;
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CLEANUP:
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return result;
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}
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double
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MediaDecoder::getAudioTimestamp(const AVPacket* packet)
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{
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AVStream* stream = mFormatContext->streams[packet->stream_index];
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double timeBase = av_q2d(stream->time_base);
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if (packet->pts == (signed)AV_NOPTS_VALUE) {
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return 0.0;
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} else {
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return packet->pts * timeBase;
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}
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}
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int
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MediaDecoder::decodeAudio(AVPacket* packet, uint8_t* buffer, int bufferSize, double* outTimestamp, int* outDataSize)
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{
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int readCount = 0;
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AVCodecContext* codecContext = mFormatContext->streams[packet->stream_index]->codec;
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while (packet->size > 0) {
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int bufSize = bufferSize - readCount;
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int size = avcodec_decode_audio3(codecContext, (int16_t*)(buffer + readCount), &bufSize, packet);
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if (size == 0) { break; }
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if (size < 0) {
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this->outputMessage(0, "avcodec_decode_audio3() failed: %d", size);
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break;
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}
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if (bufSize < 0) { continue; }
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packet->size -= size;
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readCount += bufSize;
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}
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double timestamp = this->getAudioTimestamp(packet);
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*outTimestamp = timestamp;
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*outDataSize = readCount;
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return 0;
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}
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int
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MediaDecoder::prepareStream(int streamIndex)
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{
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int intRet;
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AVStream* stream = mFormatContext->streams[streamIndex];
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AVCodecContext* codecContext = stream->codec;
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AVCodec* codec = avcodec_find_decoder(codecContext->codec_id);
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if (!codec) {
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this->outputMessage(0, "Failed to find decoder: codec_id=%d", codecContext->codec_id);
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return -1;
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}
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// Handle truncated bitstreams
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if (codec->capabilities & CODEC_CAP_TRUNCATED) {
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codecContext->flags |= CODEC_FLAG_TRUNCATED;
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}
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codecContext->debug = 0;
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codecContext->debug_mv = 0;
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codecContext->lowres = 0; // lowres decoding: 1->1/2 2->1/4
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codecContext->workaround_bugs = 1;
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codecContext->idct_algo = FF_IDCT_AUTO;
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codecContext->skip_frame = AVDISCARD_DEFAULT;
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codecContext->skip_idct = AVDISCARD_DEFAULT;
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codecContext->skip_loop_filter = AVDISCARD_DEFAULT;
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codecContext->error_recognition = FF_ER_CAREFUL;
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codecContext->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
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// open the codec.
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if (0 > (intRet = avcodec_open(codecContext, codec))) {
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this->outputMessage(0, "avcodec_open() failed: %d", intRet);
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return intRet;
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}
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return 0;
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}
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