Fix packet sorting in Mux.

Packets cannot be compared based on dts/pts alone; they also need
to take the timebase into account. (Right now, this is harmless,
but we need more precise packet sorting in the next commit.)

diff --git a/mux.cpp b/mux.cpp
index b9860b943c402f08f8263de63ccd40aca3719c3b..326c73f69cf2e4be34004bb209359a0751b838c4 100644 (file)
--- a/mux.cpp
+++ b/mux.cpp
@@ -11,6 +11,24 @@
 
 using namespace std;
 
+struct PacketBefore {
+       PacketBefore(const AVFormatContext *ctx) : ctx(ctx) {}
+
+       bool operator() (const AVPacket *a, const AVPacket *b) const {
+               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;
+               AVRational b_timebase = ctx->streams[b->stream_index]->time_base;
+               if (av_compare_ts(a_dts, a_timebase, b_dts, b_timebase) != 0) {
+                       return av_compare_ts(a_dts, a_timebase, b_dts, b_timebase) < 0;
+               } else {
+                       return av_compare_ts(a->pts, a_timebase, b->pts, b_timebase) < 0;
+               }
+       }
+
+       const AVFormatContext * const ctx;
+};
+
 Mux::Mux(AVFormatContext *avctx, int width, int height, Codec video_codec, const string &video_extradata, const AVCodecContext *audio_ctx, int time_base, KeyFrameSignalReceiver *keyframe_signal_receiver)
        : avctx(avctx), keyframe_signal_receiver(keyframe_signal_receiver)
 {
@@ -134,15 +152,7 @@ void Mux::unplug()
        }
        assert(plug_count >= 0);
 
-       sort(plugged_packets.begin(), plugged_packets.end(), [](const AVPacket *a, const AVPacket *b) {
-               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);
-               if (a_dts != b_dts) {
-                       return a_dts < b_dts;
-               } else {
-                       return a->pts < b->pts;
-               }
-       });
+       sort(plugged_packets.begin(), plugged_packets.end(), PacketBefore(avctx));
 
        for (AVPacket *pkt : plugged_packets) {
                if (av_interleaved_write_frame(avctx, pkt) < 0) {