]> git.sesse.net Git - nageru/blobdiff - ffmpeg_capture.cpp
Fix an issue where the mixer lagging too much behind CEF would cause us to display...
[nageru] / ffmpeg_capture.cpp
index 0fe74a7a95b46e3a891425ed60f7dbb6408ff95d..1ffa9d5418dc8d16cf215fb84892346c89084cb8 100644 (file)
@@ -18,6 +18,7 @@ extern "C" {
 #include <libavutil/imgutils.h>
 #include <libavutil/mem.h>
 #include <libavutil/pixfmt.h>
+#include <libavutil/opt.h>
 #include <libswscale/swscale.h>
 }
 
@@ -31,6 +32,8 @@ extern "C" {
 #include "ffmpeg_util.h"
 #include "flags.h"
 #include "image_input.h"
+#include "ref_counted_frame.h"
+#include "timebase.h"
 
 #define FRAME_SIZE (8 << 20)  // 8 MB.
 
@@ -71,6 +74,9 @@ AVPixelFormat decide_dst_format(AVPixelFormat src_format, bmusb::PixelFormat dst
        if (dst_format_type == bmusb::PixelFormat_8BitBGRA) {
                return AV_PIX_FMT_BGRA;
        }
+       if (dst_format_type == FFmpegCapture::PixelFormat_NV12) {
+               return AV_PIX_FMT_NV12;
+       }
 
        assert(dst_format_type == bmusb::PixelFormat_8BitYCbCrPlanar);
 
@@ -200,7 +206,7 @@ YCbCrFormat decode_ycbcr_format(const AVPixFmtDescriptor *desc, const AVFrame *f
 }  // namespace
 
 FFmpegCapture::FFmpegCapture(const string &filename, unsigned width, unsigned height)
-       : filename(filename), width(width), height(height)
+       : filename(filename), width(width), height(height), video_timebase{1, 1}
 {
        // Not really used for anything.
        description = "Video: " + filename;
@@ -213,6 +219,7 @@ FFmpegCapture::~FFmpegCapture()
        if (has_dequeue_callbacks) {
                dequeue_cleanup_callback();
        }
+       avresample_free(&resampler);
 }
 
 void FFmpegCapture::configure_card()
@@ -222,7 +229,8 @@ void FFmpegCapture::configure_card()
                set_video_frame_allocator(owned_video_frame_allocator.get());
        }
        if (audio_frame_allocator == nullptr) {
-               owned_audio_frame_allocator.reset(new MallocFrameAllocator(65536, NUM_QUEUED_AUDIO_FRAMES));
+               // Audio can come out in pretty large chunks, so increase from the default 1 MB.
+               owned_audio_frame_allocator.reset(new MallocFrameAllocator(1 << 20, NUM_QUEUED_AUDIO_FRAMES));
                set_audio_frame_allocator(owned_audio_frame_allocator.get());
        }
 }
@@ -313,7 +321,7 @@ void FFmpegCapture::send_disconnected_frame()
                video_frame.len = width * height * 4;
                memset(video_frame.data, 0, video_frame.len);
 
-               frame_callback(timecode++,
+               frame_callback(-1, AVRational{1, TIMEBASE}, -1, AVRational{1, TIMEBASE}, timecode++,
                        video_frame, /*video_offset=*/0, video_format,
                        FrameAllocator::Frame(), /*audio_offset=*/0, AudioFormat());
        }
@@ -350,104 +358,79 @@ bool FFmpegCapture::play_video(const string &pathname)
                return false;
        }
 
-       const AVCodecParameters *codecpar = format_ctx->streams[video_stream_index]->codecpar;
-       AVRational video_timebase = format_ctx->streams[video_stream_index]->time_base;
-       AVCodecContextWithDeleter codec_ctx = avcodec_alloc_context3_unique(nullptr);
-       if (avcodec_parameters_to_context(codec_ctx.get(), codecpar) < 0) {
-               fprintf(stderr, "%s: Cannot fill codec parameters\n", pathname.c_str());
+       int audio_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_AUDIO);
+
+       // Open video decoder.
+       const AVCodecParameters *video_codecpar = format_ctx->streams[video_stream_index]->codecpar;
+       AVCodec *video_codec = avcodec_find_decoder(video_codecpar->codec_id);
+       video_timebase = format_ctx->streams[video_stream_index]->time_base;
+       AVCodecContextWithDeleter video_codec_ctx = avcodec_alloc_context3_unique(nullptr);
+       if (avcodec_parameters_to_context(video_codec_ctx.get(), video_codecpar) < 0) {
+               fprintf(stderr, "%s: Cannot fill video codec parameters\n", pathname.c_str());
                return false;
        }
-       AVCodec *codec = avcodec_find_decoder(codecpar->codec_id);
-       if (codec == nullptr) {
-               fprintf(stderr, "%s: Cannot find decoder\n", pathname.c_str());
+       if (video_codec == nullptr) {
+               fprintf(stderr, "%s: Cannot find video decoder\n", pathname.c_str());
                return false;
        }
-       if (avcodec_open2(codec_ctx.get(), codec, nullptr) < 0) {
-               fprintf(stderr, "%s: Cannot open decoder\n", pathname.c_str());
+       if (avcodec_open2(video_codec_ctx.get(), video_codec, nullptr) < 0) {
+               fprintf(stderr, "%s: Cannot open video decoder\n", pathname.c_str());
                return false;
        }
-       unique_ptr<AVCodecContext, decltype(avcodec_close)*> codec_ctx_cleanup(
-               codec_ctx.get(), avcodec_close);
+       unique_ptr<AVCodecContext, decltype(avcodec_close)*> video_codec_ctx_cleanup(
+               video_codec_ctx.get(), avcodec_close);
+
+       // Open audio decoder, if we have audio.
+       AVCodecContextWithDeleter audio_codec_ctx = avcodec_alloc_context3_unique(nullptr);
+       if (audio_stream_index != -1) {
+               const AVCodecParameters *audio_codecpar = format_ctx->streams[audio_stream_index]->codecpar;
+               audio_timebase = format_ctx->streams[audio_stream_index]->time_base;
+               if (avcodec_parameters_to_context(audio_codec_ctx.get(), audio_codecpar) < 0) {
+                       fprintf(stderr, "%s: Cannot fill audio codec parameters\n", pathname.c_str());
+                       return false;
+               }
+               AVCodec *audio_codec = avcodec_find_decoder(audio_codecpar->codec_id);
+               if (audio_codec == nullptr) {
+                       fprintf(stderr, "%s: Cannot find audio decoder\n", pathname.c_str());
+                       return false;
+               }
+               if (avcodec_open2(audio_codec_ctx.get(), audio_codec, nullptr) < 0) {
+                       fprintf(stderr, "%s: Cannot open audio decoder\n", pathname.c_str());
+                       return false;
+               }
+       }
+       unique_ptr<AVCodecContext, decltype(avcodec_close)*> audio_codec_ctx_cleanup(
+               audio_codec_ctx.get(), avcodec_close);
 
        internal_rewind();
-       double rate = 1.0;
-
-       unique_ptr<SwsContext, decltype(sws_freeContext)*> sws_ctx(nullptr, sws_freeContext);
-       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()) {
-               // Process any queued commands from other threads.
-               vector<QueuedCommand> commands;
-               {
-                       lock_guard<mutex> lock(queue_mu);
-                       swap(commands, command_queue);
+               if (process_queued_commands(format_ctx.get(), pathname, last_modified, /*rewound=*/nullptr)) {
+                       return true;
                }
-               for (const QueuedCommand &cmd : commands) {
-                       switch (cmd.command) {
-                       case QueuedCommand::REWIND:
-                               if (av_seek_frame(format_ctx.get(), /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
-                                       fprintf(stderr, "%s: Rewind failed, stopping play.\n", pathname.c_str());
-                               }
-                               // If the file has changed since last time, return to get it reloaded.
-                               // Note that depending on how you move the file into place, you might
-                               // end up corrupting the one you're already playing, so this path
-                               // might not trigger.
-                               if (changed_since(pathname, last_modified)) {
-                                       return true;
-                               }
-                               internal_rewind();
-                               break;
+               UniqueFrame audio_frame = audio_frame_allocator->alloc_frame();
+               AudioFormat audio_format;
 
-                       case QueuedCommand::CHANGE_RATE:
-                               start = next_frame_start;
-                               pts_origin = last_pts;
-                               rate = cmd.new_rate;
-                               break;
-                       }
+               int64_t audio_pts;
+               bool error;
+               AVFrameWithDeleter frame = decode_frame(format_ctx.get(), video_codec_ctx.get(), audio_codec_ctx.get(),
+                       pathname, video_stream_index, audio_stream_index, audio_frame.get(), &audio_format, &audio_pts, &error);
+               if (error) {
+                       return false;
                }
-
-               // Read packets until we have a frame or there are none left.
-               int frame_finished = 0;
-               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.get(), &pkt) == 0) {
-                               if (pkt.stream_index != video_stream_index) {
-                                       // Ignore audio for now.
-                                       continue;
-                               }
-                               if (avcodec_send_packet(codec_ctx.get(), &pkt) < 0) {
-                                       fprintf(stderr, "%s: Cannot send packet to codec.\n", pathname.c_str());
-                                       return false;
-                               }
-                       } else {
-                               eof = true;  // Or error, but ignore that for the time being.
-                       }
-
-                       int err = avcodec_receive_frame(codec_ctx.get(), 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());
-                               return false;
-                       }
-               } while (!eof);
-
-               if (!frame_finished) {
+               if (frame == nullptr) {
                        // EOF. Loop back to the start if we can.
                        if (av_seek_frame(format_ctx.get(), /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
                                fprintf(stderr, "%s: Rewind failed, not looping.\n", pathname.c_str());
                                return true;
                        }
+                       if (video_codec_ctx != nullptr) {
+                               avcodec_flush_buffers(video_codec_ctx.get());
+                       }
+                       if (audio_codec_ctx != nullptr) {
+                               avcodec_flush_buffers(audio_codec_ctx.get());
+                       }
                        // If the file has changed since last time, return to get it reloaded.
                        // Note that depending on how you move the file into place, you might
                        // end up corrupting the one you're already playing, so this path
@@ -459,93 +442,349 @@ bool FFmpegCapture::play_video(const string &pathname)
                        continue;
                }
 
-               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());
+               VideoFormat video_format = construct_video_format(frame.get(), video_timebase);
+               UniqueFrame video_frame = make_video_frame(frame.get(), pathname, &error);
+               if (error) {
                        return false;
                }
 
-               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;
+               for ( ;; ) {
+                       if (last_pts == 0 && pts_origin == 0) {
+                               pts_origin = frame->pts;        
+                       }
+                       next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
+                       video_frame->received_timestamp = next_frame_start;
+                       bool finished_wakeup = producer_thread_should_quit.sleep_until(next_frame_start);
+                       if (finished_wakeup) {
+                               if (audio_frame->len > 0) {
+                                       assert(audio_pts != -1);
+                               }
+                               frame_callback(frame->pts, video_timebase, audio_pts, audio_timebase, timecode++,
+                                       video_frame.get_and_release(), 0, video_format,
+                                       audio_frame.get_and_release(), 0, audio_format);
+                               break;
+                       } else {
+                               if (producer_thread_should_quit.should_quit()) break;
+
+                               bool rewound = false;
+                               if (process_queued_commands(format_ctx.get(), pathname, last_modified, &rewound)) {
+                                       return true;
+                               }
+                               // If we just rewound, drop this frame on the floor and be done.
+                               if (rewound) {
+                                       break;
+                               }
+                               // OK, we didn't, so probably a rate change. Recalculate next_frame_start,
+                               // but if it's now in the past, we'll reset the origin, so that we don't
+                               // generate a huge backlog of frames that we need to run through quickly.
+                               next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
+                               steady_clock::time_point now = steady_clock::now();
+                               if (next_frame_start < now) {
+                                       pts_origin = frame->pts;
+                                       start = next_frame_start = now;
+                               }
+                       }
                }
-               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) {
-                       // Invalid frame rate.
-                       video_format.frame_rate_nom = 60;
-                       video_format.frame_rate_den = 1;
+               last_pts = frame->pts;
+       }
+       return true;
+}
+
+void FFmpegCapture::internal_rewind()
+{                              
+       pts_origin = last_pts = 0;
+       start = next_frame_start = steady_clock::now();
+}
+
+bool FFmpegCapture::process_queued_commands(AVFormatContext *format_ctx, const std::string &pathname, timespec last_modified, bool *rewound)
+{
+       // Process any queued commands from other threads.
+       vector<QueuedCommand> commands;
+       {
+               lock_guard<mutex> lock(queue_mu);
+               swap(commands, command_queue);
+       }
+       for (const QueuedCommand &cmd : commands) {
+               switch (cmd.command) {
+               case QueuedCommand::REWIND:
+                       if (av_seek_frame(format_ctx, /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
+                               fprintf(stderr, "%s: Rewind failed, stopping play.\n", pathname.c_str());
+                       }
+                       // If the file has changed since last time, return to get it reloaded.
+                       // Note that depending on how you move the file into place, you might
+                       // end up corrupting the one you're already playing, so this path
+                       // might not trigger.
+                       if (changed_since(pathname, last_modified)) {
+                               return true;
+                       }
+                       internal_rewind();
+                       if (rewound != nullptr) {
+                               *rewound = true;
+                       }
+                       break;
+
+               case QueuedCommand::CHANGE_RATE:
+                       // Change the origin to the last played frame.
+                       start = compute_frame_start(last_pts, pts_origin, video_timebase, start, rate);
+                       pts_origin = last_pts;
+                       rate = cmd.new_rate;
+                       break;
                }
-               video_format.has_signal = true;
-               video_format.is_connected = true;
+       }
+       return false;
+}
 
-               next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
-               last_pts = frame->pts;
+namespace {
 
-               FrameAllocator::Frame video_frame = video_frame_allocator->alloc_frame();
-               if (video_frame.data != nullptr) {
-                       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);
+}  // namespace
 
-                               int chroma_width = AV_CEIL_RSHIFT(int(width), desc->log2_chroma_w);
-                               int chroma_height = AV_CEIL_RSHIFT(int(height), desc->log2_chroma_h);
+AVFrameWithDeleter FFmpegCapture::decode_frame(AVFormatContext *format_ctx, AVCodecContext *video_codec_ctx, AVCodecContext *audio_codec_ctx,
+       const std::string &pathname, int video_stream_index, int audio_stream_index,
+       FrameAllocator::Frame *audio_frame, AudioFormat *audio_format, int64_t *audio_pts, bool *error)
+{
+       *error = false;
+
+       // Read packets until we have a frame or there are none left.
+       bool frame_finished = false;
+       AVFrameWithDeleter audio_avframe = av_frame_alloc_unique();
+       AVFrameWithDeleter video_avframe = av_frame_alloc_unique();
+       bool eof = false;
+       *audio_pts = -1;
+       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 == audio_stream_index && audio_callback != nullptr) {
+                               audio_callback(&pkt, format_ctx->streams[audio_stream_index]->time_base);
+                       }
+                       if (pkt.stream_index == video_stream_index) {
+                               if (avcodec_send_packet(video_codec_ctx, &pkt) < 0) {
+                                       fprintf(stderr, "%s: Cannot send packet to video codec.\n", pathname.c_str());
+                                       *error = true;
+                                       return AVFrameWithDeleter(nullptr);
+                               }
+                       } else if (pkt.stream_index == audio_stream_index) {
+                               if (*audio_pts == -1) {
+                                       *audio_pts = pkt.pts;
+                               }
+                               if (avcodec_send_packet(audio_codec_ctx, &pkt) < 0) {
+                                       fprintf(stderr, "%s: Cannot send packet to audio codec.\n", pathname.c_str());
+                                       *error = true;
+                                       return AVFrameWithDeleter(nullptr);
+                               }
+                       }
+               } else {
+                       eof = true;  // Or error, but ignore that for the time being.
+               }
 
-                               pic_data[0] = video_frame.data;
-                               linesizes[0] = width;
+               // Decode audio, if any.
+               if (*audio_pts != -1) {
+                       for ( ;; ) {
+                               int err = avcodec_receive_frame(audio_codec_ctx, audio_avframe.get());
+                               if (err == 0) {
+                                       convert_audio(audio_avframe.get(), audio_frame, audio_format);
+                               } else if (err == AVERROR(EAGAIN)) {
+                                       break;
+                               } else {
+                                       fprintf(stderr, "%s: Cannot receive frame from audio codec.\n", pathname.c_str());
+                                       *error = true;
+                                       return AVFrameWithDeleter(nullptr);
+                               }
+                       }
+               }
 
-                               pic_data[1] = pic_data[0] + width * height;
-                               linesizes[1] = chroma_width;
+               // Decode video, if we have a frame.
+               int err = avcodec_receive_frame(video_codec_ctx, video_avframe.get());
+               if (err == 0) {
+                       frame_finished = true;
+                       break;
+               } else if (err != AVERROR(EAGAIN)) {
+                       fprintf(stderr, "%s: Cannot receive frame from video codec.\n", pathname.c_str());
+                       *error = true;
+                       return AVFrameWithDeleter(nullptr);
+               }
+       } while (!eof);
 
-                               pic_data[2] = pic_data[1] + chroma_width * chroma_height;
-                               linesizes[2] = chroma_width;
+       if (frame_finished)
+               return video_avframe;
+       else
+               return AVFrameWithDeleter(nullptr);
+}
 
-                               video_frame.len = width * height + 2 * chroma_width * chroma_height;
+void FFmpegCapture::convert_audio(const AVFrame *audio_avframe, FrameAllocator::Frame *audio_frame, AudioFormat *audio_format)
+{
+       // Decide on a format. If there already is one in this audio frame,
+       // we're pretty much forced to use it. If not, we try to find an exact match.
+       // If that still doesn't work, we default to 32-bit signed chunked
+       // (float would be nice, but there's really no way to signal that yet).
+       AVSampleFormat dst_format;
+       if (audio_format->bits_per_sample == 0) {
+               switch (audio_avframe->format) {
+               case AV_SAMPLE_FMT_S16:
+               case AV_SAMPLE_FMT_S16P:
+                       audio_format->bits_per_sample = 16;
+                       dst_format = AV_SAMPLE_FMT_S16;
+                       break;
+               case AV_SAMPLE_FMT_S32:
+               case AV_SAMPLE_FMT_S32P:
+               default:
+                       audio_format->bits_per_sample = 32;
+                       dst_format = AV_SAMPLE_FMT_S32;
+                       break;
+               }
+       } else if (audio_format->bits_per_sample == 16) {
+               dst_format = AV_SAMPLE_FMT_S16;
+       } else if (audio_format->bits_per_sample == 32) {
+               dst_format = AV_SAMPLE_FMT_S32;
+       } else {
+               assert(false);
+       }
+       audio_format->num_channels = 2;
 
-                               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.received_timestamp = next_frame_start;
+       int64_t channel_layout = audio_avframe->channel_layout;
+       if (channel_layout == 0) {
+               channel_layout = av_get_default_channel_layout(audio_avframe->channels);
+       }
+
+       if (resampler == nullptr ||
+           audio_avframe->format != last_src_format ||
+           dst_format != last_dst_format ||
+           channel_layout != last_channel_layout ||
+           av_frame_get_sample_rate(audio_avframe) != last_sample_rate) {
+               avresample_free(&resampler);
+               resampler = avresample_alloc_context();
+               if (resampler == nullptr) {
+                       fprintf(stderr, "Allocating resampler failed.\n");
+                       exit(1);
                }
 
-               FrameAllocator::Frame audio_frame;
-               AudioFormat audio_format;
-                audio_format.bits_per_sample = 32;
-                audio_format.num_channels = 8;
+               av_opt_set_int(resampler, "in_channel_layout",  channel_layout,                             0);
+               av_opt_set_int(resampler, "out_channel_layout", AV_CH_LAYOUT_STEREO,                        0);
+               av_opt_set_int(resampler, "in_sample_rate",     av_frame_get_sample_rate(audio_avframe),    0);
+               av_opt_set_int(resampler, "out_sample_rate",    OUTPUT_FREQUENCY,                           0);
+               av_opt_set_int(resampler, "in_sample_fmt",      audio_avframe->format,                      0);
+               av_opt_set_int(resampler, "out_sample_fmt",     dst_format,                                 0);
+
+               if (avresample_open(resampler) < 0) {
+                       fprintf(stderr, "Could not open resample context.\n");
+                       exit(1);
+               }
 
-               producer_thread_should_quit.sleep_until(next_frame_start);
-               frame_callback(timecode++,
-                       video_frame, 0, video_format,
-                       audio_frame, 0, audio_format);
+               last_src_format = AVSampleFormat(audio_avframe->format);
+               last_dst_format = dst_format;
+               last_channel_layout = channel_layout;
+               last_sample_rate = av_frame_get_sample_rate(audio_avframe);
        }
-       return true;
+
+       size_t bytes_per_sample = (audio_format->bits_per_sample / 8) * 2;
+       size_t num_samples_room = (audio_frame->size - audio_frame->len) / bytes_per_sample;
+
+       uint8_t *data = audio_frame->data + audio_frame->len;
+       int out_samples = avresample_convert(resampler, &data, 0, num_samples_room,
+               const_cast<uint8_t **>(audio_avframe->data), audio_avframe->linesize[0], audio_avframe->nb_samples);
+       if (out_samples < 0) {
+                fprintf(stderr, "Audio conversion failed.\n");
+                exit(1);
+        }
+
+       audio_frame->len += out_samples * bytes_per_sample;
 }
 
-void FFmpegCapture::internal_rewind()
-{                              
-       pts_origin = last_pts = 0;
-       start = next_frame_start = steady_clock::now();
+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 if (pixel_format == FFmpegCapture::PixelFormat_NV12) {
+               video_format.stride = width;
+       } 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;
+}
+
+UniqueFrame FFmpegCapture::make_video_frame(const AVFrame *frame, const string &pathname, bool *error)
+{
+       *error = false;
+
+       UniqueFrame 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 if (pixel_format == PixelFormat_NV12) {
+               pic_data[0] = video_frame->data;
+               linesizes[0] = width;
+
+               pic_data[1] = pic_data[0] + width * height;
+               linesizes[1] = width;
+
+               video_frame->len = (width * 2) * height;
+
+               const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
+               current_frame_ycbcr_format = decode_ycbcr_format(desc, frame);
+       } 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;
 }