+
+AVFrameWithDeleter FFmpegCapture::decode_frame(AVFormatContext *format_ctx, AVCodecContext *codec_ctx, const std::string &pathname, int video_stream_index, bool *error)
+{
+ *error = false;
+
+ // Read packets until we have a frame or there are none left.
+ bool frame_finished = false;
+ AVFrameWithDeleter frame = av_frame_alloc_unique();
+ bool eof = false;
+ do {
+ AVPacket pkt;
+ unique_ptr<AVPacket, decltype(av_packet_unref)*> pkt_cleanup(
+ &pkt, av_packet_unref);
+ av_init_packet(&pkt);
+ pkt.data = nullptr;
+ pkt.size = 0;
+ if (av_read_frame(format_ctx, &pkt) == 0) {
+ if (pkt.stream_index != video_stream_index) {
+ // Ignore audio for now.
+ continue;
+ }
+ if (avcodec_send_packet(codec_ctx, &pkt) < 0) {
+ fprintf(stderr, "%s: Cannot send packet to codec.\n", pathname.c_str());
+ *error = true;
+ return AVFrameWithDeleter(nullptr);
+ }
+ } else {
+ eof = true; // Or error, but ignore that for the time being.
+ }
+
+ int err = avcodec_receive_frame(codec_ctx, frame.get());
+ if (err == 0) {
+ frame_finished = true;
+ break;
+ } else if (err != AVERROR(EAGAIN)) {
+ fprintf(stderr, "%s: Cannot receive frame from codec.\n", pathname.c_str());
+ *error = true;
+ return AVFrameWithDeleter(nullptr);
+ }
+ } while (!eof);
+
+ if (frame_finished)
+ return frame;
+ else
+ return AVFrameWithDeleter(nullptr);
+}
+
+VideoFormat FFmpegCapture::construct_video_format(const AVFrame *frame, AVRational video_timebase)
+{
+ VideoFormat video_format;
+ video_format.width = width;
+ video_format.height = height;
+ if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
+ video_format.stride = width * 4;
+ } else {
+ assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
+ video_format.stride = width;
+ }
+ video_format.frame_rate_nom = video_timebase.den;
+ video_format.frame_rate_den = av_frame_get_pkt_duration(frame) * video_timebase.num;
+ if (video_format.frame_rate_nom == 0 || video_format.frame_rate_den == 0) {
+ // Invalid frame rate.
+ video_format.frame_rate_nom = 60;
+ video_format.frame_rate_den = 1;
+ }
+ video_format.has_signal = true;
+ video_format.is_connected = true;
+ return video_format;
+}
+
+FrameAllocator::Frame FFmpegCapture::make_video_frame(const AVFrame *frame, const string &pathname, bool *error)
+{
+ *error = false;
+
+ FrameAllocator::Frame video_frame = video_frame_allocator->alloc_frame();
+ if (video_frame.data == nullptr) {
+ return video_frame;
+ }
+
+ if (sws_ctx == nullptr ||
+ sws_last_width != frame->width ||
+ sws_last_height != frame->height ||
+ sws_last_src_format != frame->format) {
+ sws_dst_format = decide_dst_format(AVPixelFormat(frame->format), pixel_format);
+ sws_ctx.reset(
+ sws_getContext(frame->width, frame->height, AVPixelFormat(frame->format),
+ width, height, sws_dst_format,
+ SWS_BICUBIC, nullptr, nullptr, nullptr));
+ sws_last_width = frame->width;
+ sws_last_height = frame->height;
+ sws_last_src_format = frame->format;
+ }
+ if (sws_ctx == nullptr) {
+ fprintf(stderr, "%s: Could not create scaler context\n", pathname.c_str());
+ *error = true;
+ return video_frame;
+ }
+
+ uint8_t *pic_data[4] = { nullptr, nullptr, nullptr, nullptr };
+ int linesizes[4] = { 0, 0, 0, 0 };
+ if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
+ pic_data[0] = video_frame.data;
+ linesizes[0] = width * 4;
+ video_frame.len = (width * 4) * height;
+ } else {
+ assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
+ const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
+
+ int chroma_width = AV_CEIL_RSHIFT(int(width), desc->log2_chroma_w);
+ int chroma_height = AV_CEIL_RSHIFT(int(height), desc->log2_chroma_h);
+
+ pic_data[0] = video_frame.data;
+ linesizes[0] = width;
+
+ pic_data[1] = pic_data[0] + width * height;
+ linesizes[1] = chroma_width;
+
+ pic_data[2] = pic_data[1] + chroma_width * chroma_height;
+ linesizes[2] = chroma_width;
+
+ video_frame.len = width * height + 2 * chroma_width * chroma_height;
+
+ current_frame_ycbcr_format = decode_ycbcr_format(desc, frame);
+ }
+ sws_scale(sws_ctx.get(), frame->data, frame->linesize, 0, frame->height, pic_data, linesizes);
+
+ return video_frame;
+}