demux: avoid a copy of demux packets with lavf, reduce padding

When demux_lavf read a new packet it used to copy the data from
libavformat's struct AVPacket to struct demux_packet and then free the
lavf packet. Change it to instead keep the AVPacket allocated and
point demux_packet fields to the buffer in that.

Also change MP_INPUT_BUFFER_PADDING_SIZE to 8 which matches
FF_INPUT_BUFFER_PADDING SIZE; demux_lavf packets won't have more
padding now anyway (it was increased from 8 earlier when
FF_INPUT_BUFFER_PADDING_SIZE was increased in libavcodec, but that
change was reverted).

1 files changed, 20 insertions, 2 deletions

diff --git a/libmpdemux/demuxer.c b/libmpdemux/demuxer.c
index c59fd3fdc7..d4c43ad657 100644
--- a/libmpdemux/demuxer.c
+++ b/libmpdemux/demuxer.c
@@ -176,7 +176,7 @@ const demuxer_desc_t *const demuxer_list[] = {
     NULL
 };
 
-struct demux_packet *new_demux_packet(size_t len)
+static struct demux_packet *create_packet(size_t len)
 {
     if (len > 1000000000) {
         mp_msg(MSGT_DEMUXER, MSGL_FATAL, "Attempt to allocate demux packet "
@@ -194,6 +194,13 @@ struct demux_packet *new_demux_packet(size_t len)
     dp->refcount = 1;
     dp->master = NULL;
     dp->buffer = NULL;
+    dp->avpacket = NULL;
+    return dp;
+}
+
+struct demux_packet *new_demux_packet(size_t len)
+{
+    struct demux_packet *dp = create_packet(len);
     dp->buffer = malloc(len + MP_INPUT_BUFFER_PADDING_SIZE);
     if (!dp->buffer) {
         mp_msg(MSGT_DEMUXER, MSGL_FATAL, "Memory allocation failure!\n");
@@ -203,6 +210,14 @@ struct demux_packet *new_demux_packet(size_t len)
     return dp;
 }
 
+// data must already have suitable padding
+struct demux_packet *new_demux_packet_fromdata(void *data, size_t len)
+{
+    struct demux_packet *dp = create_packet(len);
+    dp->buffer = data;
+    return dp;
+}
+
 void resize_demux_packet(struct demux_packet *dp, size_t len)
 {
     if (len > 1000000000) {
@@ -237,7 +252,10 @@ void free_demux_packet(struct demux_packet *dp)
     if (dp->master == NULL) {  //dp is a master packet
         dp->refcount--;
         if (dp->refcount == 0) {
-            free(dp->buffer);
+            if (dp->avpacket)
+                talloc_free(dp->avpacket);
+            else
+                free(dp->buffer);
             free(dp);
         }
         return;