struct PacketBefore {
PacketBefore(const AVFormatContext *ctx) : ctx(ctx) {}
- bool operator() (const AVPacket *a, const AVPacket *b) const {
+ bool operator() (const Mux::QueuedPacket &a_qp, const Mux::QueuedPacket &b_qp) const {
+ const AVPacket *a = a_qp.pkt;
+ const AVPacket *b = b_qp.pkt;
int64_t a_dts = (a->dts == AV_NOPTS_VALUE ? a->pts : a->dts);
int64_t b_dts = (b->dts == AV_NOPTS_VALUE ? b->pts : b->dts);
AVRational a_timebase = ctx->streams[a->stream_index]->time_base;
const AVFormatContext * const ctx;
};
-Mux::Mux(AVFormatContext *avctx, int width, int height, Codec video_codec, const string &video_extradata, const AVCodecParameters *audio_codecpar, int time_base, std::function<void(int64_t)> write_callback, const vector<MuxMetrics *> &metrics)
- : avctx(avctx), write_callback(write_callback), metrics(metrics)
+Mux::Mux(AVFormatContext *avctx, int width, int height, Codec video_codec, const string &video_extradata, const AVCodecParameters *audio_codecpar, int time_base, std::function<void(int64_t)> write_callback, WriteStrategy write_strategy, const vector<MuxMetrics *> &metrics)
+ : write_strategy(write_strategy), avctx(avctx), write_callback(write_callback), metrics(metrics)
{
avstream_video = avformat_new_stream(avctx, nullptr);
if (avstream_video == nullptr) {
// Make sure the header is written before the constructor exits.
avio_flush(avctx->pb);
+
+ if (write_strategy == WRITE_BACKGROUND) {
+ writer_thread = thread(&Mux::thread_func, this);
+ }
}
Mux::~Mux()
{
+ assert(plug_count == 0);
+ if (write_strategy == WRITE_BACKGROUND) {
+ writer_thread_should_quit = true;
+ packet_queue_ready.notify_all();
+ writer_thread.join();
+ }
int64_t old_pos = avctx->pb->pos;
av_write_trailer(avctx);
for (MuxMetrics *metric : metrics) {
{
lock_guard<mutex> lock(mu);
- if (plug_count > 0) {
- plugged_packets.push_back(av_packet_clone(&pkt_copy));
+ if (write_strategy == WriteStrategy::WRITE_BACKGROUND) {
+ packet_queue.push_back(QueuedPacket{ av_packet_clone(&pkt_copy), pts });
+ if (plug_count == 0) packet_queue_ready.notify_all();
+ } else if (plug_count > 0) {
+ packet_queue.push_back(QueuedPacket{ av_packet_clone(&pkt_copy), pts });
} else {
- write_packet_or_die(pkt_copy);
+ write_packet_or_die(pkt_copy, pts);
}
}
av_packet_unref(&pkt_copy);
-
- // Note: This will be wrong in the case of plugged packets, but that only happens
- // for network streams, not for files, and write callbacks are only really relevant
- // for files. (We don't want to do this from write_packet_or_die, as it only has
- // the rescaled pts, which is unsuitable for callback.)
- if (pkt.stream_index == 0 && write_callback != nullptr) {
- write_callback(pts);
- }
}
-void Mux::write_packet_or_die(const AVPacket &pkt)
+void Mux::write_packet_or_die(const AVPacket &pkt, int64_t unscaled_pts)
{
for (MuxMetrics *metric : metrics) {
if (pkt.stream_index == 0) {
for (MuxMetrics *metric : metrics) {
metric->metric_written_bytes += avctx->pb->pos - old_pos;
}
+
+ if (pkt.stream_index == 0 && write_callback != nullptr) {
+ write_callback(unscaled_pts);
+ }
}
void Mux::plug()
}
assert(plug_count >= 0);
- sort(plugged_packets.begin(), plugged_packets.end(), PacketBefore(avctx));
+ sort(packet_queue.begin(), packet_queue.end(), PacketBefore(avctx));
- for (AVPacket *pkt : plugged_packets) {
- write_packet_or_die(*pkt);
- av_packet_free(&pkt);
+ if (write_strategy == WRITE_BACKGROUND) {
+ packet_queue_ready.notify_all();
+ } else {
+ for (QueuedPacket &qp : packet_queue) {
+ write_packet_or_die(*qp.pkt, qp.unscaled_pts);
+ av_packet_free(&qp.pkt);
+ }
+ packet_queue.clear();
+ }
+}
+
+void Mux::thread_func()
+{
+ unique_lock<mutex> lock(mu);
+ for ( ;; ) {
+ packet_queue_ready.wait(lock, [this]() {
+ return writer_thread_should_quit || (!packet_queue.empty() && plug_count == 0);
+ });
+ if (writer_thread_should_quit && packet_queue.empty()) {
+ // All done.
+ break;
+ }
+
+ assert(!packet_queue.empty() && plug_count == 0);
+ vector<QueuedPacket> packets;
+ swap(packets, packet_queue);
+
+ lock.unlock();
+ for (QueuedPacket &qp : packets) {
+ write_packet_or_die(*qp.pkt, qp.unscaled_pts);
+ av_packet_free(&qp.pkt);
+ }
+ lock.lock();
}
- plugged_packets.clear();
}
void MuxMetrics::init(const vector<pair<string, string>> &labels)
#include <sys/types.h>
#include <atomic>
+#include <condition_variable>
#include <functional>
#include <mutex>
#include <string>
#include <utility>
+#include <thread>
#include <vector>
struct MuxMetrics {
CODEC_H264,
CODEC_NV12, // Uncompressed 4:2:0.
};
+ enum WriteStrategy {
+ // add_packet() will write the packet immediately, unless plugged.
+ WRITE_FOREGROUND,
+
+ // All writes will happen on a separate thread, so add_packet()
+ // won't block. Use this if writing to a file and you might be
+ // holding a mutex (because blocking I/O with a mutex held is
+ // not good). Note that this will clone every packet, so it has
+ // higher overhead.
+ WRITE_BACKGROUND,
+ };
// Takes ownership of avctx. <write_callback> will be called every time
// a write has been made to the video stream (id 0), with the pts of
// the just-written frame. (write_callback can be nullptr.)
// Does not take ownership of <metrics>; elements in there, if any,
// will be added to.
- Mux(AVFormatContext *avctx, int width, int height, Codec video_codec, const std::string &video_extradata, const AVCodecParameters *audio_codecpar, int time_base, std::function<void(int64_t)> write_callback, const std::vector<MuxMetrics *> &metrics);
+ Mux(AVFormatContext *avctx, int width, int height, Codec video_codec, const std::string &video_extradata, const AVCodecParameters *audio_codecpar, int time_base, std::function<void(int64_t)> write_callback, WriteStrategy write_strategy, const std::vector<MuxMetrics *> &metrics);
~Mux();
void add_packet(const AVPacket &pkt, int64_t pts, int64_t dts);
void unplug();
private:
- void write_packet_or_die(const AVPacket &pkt); // Must be called with <mu> held.
+ // If write_strategy == WRITE_FOREGORUND, Must be called with <mu> held.
+ void write_packet_or_die(const AVPacket &pkt, int64_t unscaled_pts);
+ void thread_func();
+
+ WriteStrategy write_strategy;
std::mutex mu;
- AVFormatContext *avctx; // Protected by <mu>.
+
+ // These are only in use if write_strategy == WRITE_BACKGROUND.
+ std::atomic<bool> writer_thread_should_quit{false};
+ std::thread writer_thread;
+
+ AVFormatContext *avctx; // Protected by <mu>, iff write_strategy == WRITE_BACKGROUND.
int plug_count = 0; // Protected by <mu>.
- std::vector<AVPacket *> plugged_packets; // Protected by <mu>.
+
+ // Protected by <mu>. If write_strategy == WRITE_FOREGROUND,
+ // this is only in use when plugging.
+ struct QueuedPacket {
+ AVPacket *pkt;
+ int64_t unscaled_pts;
+ };
+ std::vector<QueuedPacket> packet_queue;
+ std::condition_variable packet_queue_ready;
AVStream *avstream_video, *avstream_audio;
std::function<void(int64_t)> write_callback;
std::vector<MuxMetrics *> metrics;
+
+ friend struct PacketBefore;
};
#endif // !defined(_MUX_H)
projects / nageru / commitdiff