]> git.sesse.net Git - nageru/blobdiff - ffmpeg_capture.cpp
Add support for decoding video as Y'CbCr. Not activated yet.
[nageru] / ffmpeg_capture.cpp
index 407f359104cff8444ac56cc9480c77c86366667c..0fe74a7a95b46e3a891425ed60f7dbb6408ff95d 100644 (file)
@@ -37,6 +37,7 @@ extern "C" {
 using namespace std;
 using namespace std::chrono;
 using namespace bmusb;
+using namespace movit;
 
 namespace {
 
@@ -59,6 +60,143 @@ bool changed_since(const std::string &pathname, const timespec &ts)
        return (buf.st_mtim.tv_sec != ts.tv_sec || buf.st_mtim.tv_nsec != ts.tv_nsec);
 }
 
+bool is_full_range(const AVPixFmtDescriptor *desc)
+{
+       // This is horrible, but there's no better way that I know of.
+       return (strchr(desc->name, 'j') != nullptr);
+}
+
+AVPixelFormat decide_dst_format(AVPixelFormat src_format, bmusb::PixelFormat dst_format_type)
+{
+       if (dst_format_type == bmusb::PixelFormat_8BitBGRA) {
+               return AV_PIX_FMT_BGRA;
+       }
+
+       assert(dst_format_type == bmusb::PixelFormat_8BitYCbCrPlanar);
+
+       // If this is a non-Y'CbCr format, just convert to 4:4:4 Y'CbCr
+       // and be done with it. It's too strange to spend a lot of time on.
+       // (Let's hope there's no alpha.)
+       const AVPixFmtDescriptor *src_desc = av_pix_fmt_desc_get(src_format);
+       if (src_desc == nullptr ||
+           src_desc->nb_components != 3 ||
+           (src_desc->flags & AV_PIX_FMT_FLAG_RGB)) {
+               return AV_PIX_FMT_YUV444P;
+       }
+
+       // The best for us would be Cb and Cr together if possible,
+       // but FFmpeg doesn't support that except in the special case of
+       // NV12, so we need to go to planar even for the case of NV12.
+       // Thus, look for the closest (but no worse) 8-bit planar Y'CbCr format
+       // that matches in color range. (This will also include the case of
+       // the source format already being acceptable.)
+       bool src_full_range = is_full_range(src_desc);
+       const char *best_format = "yuv444p";
+       unsigned best_score = numeric_limits<unsigned>::max();
+       for (const AVPixFmtDescriptor *desc = av_pix_fmt_desc_next(nullptr);
+            desc;
+            desc = av_pix_fmt_desc_next(desc)) {
+               // Find planar Y'CbCr formats only.
+               if (desc->nb_components != 3) continue;
+               if (desc->flags & AV_PIX_FMT_FLAG_RGB) continue;
+               if (!(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) continue;
+               if (desc->comp[0].plane != 0 ||
+                   desc->comp[1].plane != 1 ||
+                   desc->comp[2].plane != 2) continue;
+
+               // 8-bit formats only.
+               if (desc->flags & AV_PIX_FMT_FLAG_BE) continue;
+               if (desc->comp[0].depth != 8) continue;
+
+               // Same or better chroma resolution only.
+               int chroma_w_diff = desc->log2_chroma_w - src_desc->log2_chroma_w;
+               int chroma_h_diff = desc->log2_chroma_h - src_desc->log2_chroma_h;
+               if (chroma_w_diff < 0 || chroma_h_diff < 0)
+                       continue;
+
+               // Matching full/limited range only.
+               if (is_full_range(desc) != src_full_range)
+                       continue;
+
+               // Pick something with as little excess chroma resolution as possible.
+               unsigned score = (1 << (chroma_w_diff)) << chroma_h_diff;
+               if (score < best_score) {
+                       best_score = score;
+                       best_format = desc->name;
+               }
+       }
+       return av_get_pix_fmt(best_format);
+}
+
+YCbCrFormat decode_ycbcr_format(const AVPixFmtDescriptor *desc, const AVFrame *frame)
+{
+       YCbCrFormat format;
+       AVColorSpace colorspace = av_frame_get_colorspace(frame);
+       switch (colorspace) {
+       case AVCOL_SPC_BT709:
+               format.luma_coefficients = YCBCR_REC_709;
+               break;
+       case AVCOL_SPC_BT470BG:
+       case AVCOL_SPC_SMPTE170M:
+       case AVCOL_SPC_SMPTE240M:
+               format.luma_coefficients = YCBCR_REC_601;
+               break;
+       case AVCOL_SPC_BT2020_NCL:
+               format.luma_coefficients = YCBCR_REC_2020;
+               break;
+       case AVCOL_SPC_UNSPECIFIED:
+               format.luma_coefficients = (frame->height >= 720 ? YCBCR_REC_709 : YCBCR_REC_601);
+               break;
+       default:
+               fprintf(stderr, "Unknown Y'CbCr coefficient enum %d from FFmpeg; choosing Rec. 709.\n",
+                       colorspace);
+               format.luma_coefficients = YCBCR_REC_709;
+               break;
+       }
+
+       format.full_range = is_full_range(desc);
+       format.num_levels = 1 << desc->comp[0].depth;
+       format.chroma_subsampling_x = 1 << desc->log2_chroma_w;
+       format.chroma_subsampling_y = 1 << desc->log2_chroma_h;
+
+       switch (frame->chroma_location) {
+       case AVCHROMA_LOC_LEFT:
+               format.cb_x_position = 0.0;
+               format.cb_y_position = 0.5;
+               break;
+       case AVCHROMA_LOC_CENTER:
+               format.cb_x_position = 0.5;
+               format.cb_y_position = 0.5;
+               break;
+       case AVCHROMA_LOC_TOPLEFT:
+               format.cb_x_position = 0.0;
+               format.cb_y_position = 0.0;
+               break;
+       case AVCHROMA_LOC_TOP:
+               format.cb_x_position = 0.5;
+               format.cb_y_position = 0.0;
+               break;
+       case AVCHROMA_LOC_BOTTOMLEFT:
+               format.cb_x_position = 0.0;
+               format.cb_y_position = 1.0;
+               break;
+       case AVCHROMA_LOC_BOTTOM:
+               format.cb_x_position = 0.5;
+               format.cb_y_position = 1.0;
+               break;
+       default:
+               fprintf(stderr, "Unknown chroma location coefficient enum %d from FFmpeg; choosing Rec. 709.\n",
+                       frame->chroma_location);
+               format.cb_x_position = 0.5;
+               format.cb_y_position = 0.5;
+               break;
+       }
+
+       format.cr_x_position = format.cb_x_position;
+       format.cr_y_position = format.cb_y_position;
+       return format;
+}
+
 }  // namespace
 
 FFmpegCapture::FFmpegCapture(const string &filename, unsigned width, unsigned height)
@@ -235,7 +373,8 @@ bool FFmpegCapture::play_video(const string &pathname)
        double rate = 1.0;
 
        unique_ptr<SwsContext, decltype(sws_freeContext)*> sws_ctx(nullptr, sws_freeContext);
-       int sws_last_width = -1, sws_last_height = -1;
+       int sws_last_width = -1, sws_last_height = -1, sws_last_src_format = -1;
+       AVPixelFormat sws_dst_format = AVPixelFormat(-1);  // In practice, always initialized.
 
        // Main loop.
        while (!producer_thread_should_quit.should_quit()) {
@@ -320,13 +459,18 @@ bool FFmpegCapture::play_video(const string &pathname)
                        continue;
                }
 
-               if (sws_ctx == nullptr || sws_last_width != frame->width || sws_last_height != frame->height) {
+               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, AV_PIX_FMT_BGRA,
+                               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());
@@ -336,7 +480,12 @@ bool FFmpegCapture::play_video(const string &pathname)
                VideoFormat video_format;
                video_format.width = width;
                video_format.height = height;
-               video_format.stride = width * 4;
+               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.get()) * video_timebase.num;
                if (video_format.frame_rate_nom == 0 || video_format.frame_rate_den == 0) {
@@ -352,10 +501,33 @@ bool FFmpegCapture::play_video(const string &pathname)
 
                FrameAllocator::Frame video_frame = video_frame_allocator->alloc_frame();
                if (video_frame.data != nullptr) {
-                       uint8_t *pic_data[4] = { video_frame.data, nullptr, nullptr, nullptr };
-                       int linesizes[4] = { int(video_format.stride), 0, 0, 0 };
+                       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] = video_format.stride;
+                               video_frame.len = video_format.stride * 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.get());
+                       }
                        sws_scale(sws_ctx.get(), frame->data, frame->linesize, 0, frame->height, pic_data, linesizes);
-                       video_frame.len = video_format.stride * height;
                        video_frame.received_timestamp = next_frame_start;
                }