From 7083f88ca8b98aa74dbc9e34d5c5cf6e150cfe0b Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 18 Jul 2014 15:10:28 +0200
Subject: video: don't block when reading video packets

Instead of blocking on the demuxer when reading a packet, let packets be
read asynchronously. Basically, it polls whether a packet is available,
and if not, the playloop goes to sleep until the demuxer thread wakes it
up.

Note that the player will still block for I/O, because audio is still
read synchronously. It's much harder to do the same change for audio
(because of the design of the audio decoding path and especially
initialization), so audio will have to be done later.
---
 player/video.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

(limited to 'player/video.c')

diff --git a/player/video.c b/player/video.c
index 3d742c0081..45cf04e92b 100644
--- a/player/video.c
+++ b/player/video.c
@@ -300,6 +300,8 @@ static int check_framedrop(struct MPContext *mpctx, double frame_time)
 
 // Read a packet, store decoded image into d_video->waiting_decoded_mpi
 // Return 0 if EOF was reached (though the decoder still can have frames buffered)
+// Return 1 if a packet was read (i.e. progress made)
+// Return 3 if the demuxer will wake us up once a new packet is available.
 static int decode_image(struct MPContext *mpctx)
 {
     struct dec_video *d_video = mpctx->d_video;
@@ -310,7 +312,9 @@ static int decode_image(struct MPContext *mpctx)
         return 0;
     }
 
-    struct demux_packet *pkt = demux_read_packet(d_video->header);
+    struct demux_packet *pkt;
+    if (demux_read_packet_async(d_video->header, &pkt) == 0)
+        return 3;
     if (pkt && pkt->pts != MP_NOPTS_VALUE)
         pkt->pts += mpctx->video_offset;
     if ((pkt && pkt->pts >= mpctx->hrseek_pts - .005) ||
@@ -326,7 +330,7 @@ static int decode_image(struct MPContext *mpctx)
     bool had_packet = !!pkt;
     talloc_free(pkt);
 
-    return had_packet;
+    return had_packet ? 1 : 0;
 }
 
 
@@ -345,7 +349,7 @@ static void init_filter_params(struct MPContext *mpctx)
 }
 
 // Make sure at least 1 filtered image is available.
-// Returns: -1: error, 0: EOF, 1: ok or progress was made
+// Returns: -1: error, 0: EOF, 1: ok or progress was made, 3: ok but wait
 // A return value of 1 doesn't necessarily output a frame, but makes the promise
 // that calling this function again will eventually do something.
 static int video_decode_and_filter(struct MPContext *mpctx)
@@ -387,9 +391,11 @@ static int video_decode_and_filter(struct MPContext *mpctx)
         return 1;
     }
 
+    int r = 1;
+
     if (!d_video->waiting_decoded_mpi) {
         // Decode a new image, or at least feed the decoder a packet.
-        int r = decode_image(mpctx);
+        r = decode_image(mpctx);
         if (d_video->waiting_decoded_mpi)
             d_video->decoder_output = d_video->waiting_decoded_mpi->params;
         if (!d_video->waiting_decoded_mpi && r < 1)
@@ -397,7 +403,7 @@ static int video_decode_and_filter(struct MPContext *mpctx)
     }
 
     // Image will be filtered on the next iteration.
-    return 1;
+    return r;
 }
 
 static void init_vo(struct MPContext *mpctx)
@@ -518,7 +524,7 @@ int update_video(struct MPContext *mpctx, double endpts, bool reconfig_ok,
     }
 
     int r = video_output_image(mpctx, endpts, reconfig_ok);
-    if (r < 0)
+    if (r < 0 || r == 3)
         return r;
 
     // On EOF (r==0), we always drain the VO; otherwise we must ensure that
-- 
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