Hi,
recently i noticed that all clips i was trying to play with mlt has
duration 1 smaller then origin.
this happens because of calculation (or even compiler) of frames count
that comes on double and later not rounded to integer.
code part of producer_avformat.c:
[...]
590: // This isn't going to be accurate for all formats
591: mlt_position frames = ( mlt_position )( ( ( double
)format->duration / ( double )AV_TIME_BASE ) * fps );
592: mlt_properties_set_position( properties, "out", frames - 1 );
[...]
that code part is compiled into something like this:
B+ x0x7ffff0afdb0b <producer_open+2123> cvtsi2sd %rsi,%xmm1
x
x0x7ffff0afdb10 <producer_open+2128> lea 0x9dd1(%rip),%rdi
# 0x7ffff0b078e8 x
x0x7ffff0afdb17 <producer_open+2135> mov $0xf4240,%edx rdx
x
x0x7ffff0afdb1c <producer_open+2140> mov %rd2,%ea(%rax)
x
x0x7ffff0afdb21 <producer_open+2145> mulsd 0xa067(%rip),%xmm1
# 0x7ffff0b07b90l_debug_state> x
x0x7ffff0afdb29 <producer_open+2153> mulsd %xmm0,%xmm1 )
x
x0x7ffff0afdb2d <producer_open+2157> cvttsd2si %xmm1,%ebp
x
>x0x7ffff0afdb31 <producer_open+2161> mov %ebp,%ecx )
x
in my case clip has 251 frame. before *cvttsd2si* xmm1 register has
value 250.99999999999997:
1: x/i $pc
=> 0x7ffff0afdb2d <producer_open+2157>: cvttsd2si %xmm1,%ebp
(gdb) print $xmm1
$5 = {v4_float = {-nan(0x7fffff), 3.74023414, 1.40129846e-45, 0},
v2_double = {250.99999999999997,
4.9406564584124654e-324}, v16_int8 = {-1, -1, -1, -1, -1, 95, 111,
64, 1, 0, 0, 0, 0, 0, 0, 0}, v8_int16 = {
-1, -1, 24575, 16495, 1, 0, 0, 0}, v4_int32 = {-1, 1081040895, 1,
0}, v2_int64 = {4643035293958537215, 1},
uint128 = 0x0000000000000001406f5fffffffffff}
but after storing into *ecx* it becode truncated:
(gdb) step
1: x/i $pc
=> 0x7ffff0afdb31 <producer_open+2161>: mov %ebp,%ecx
(gdb) print $ebp
$6 = 250
attached patch tries to avoid double type using during calculation and
properly return 251 frames length...
--
________________________________________
Maksym Veremeyenko
>From b6c261c1224e27bf877a3647870d0699d1058215 Mon Sep 17 00:00:00 2001
From: Maksym Veremeyenko <ve...@m1stereo.tv>
Date: Thu, 18 Jul 2013 15:03:40 +0300
Subject: [PATCH] use rational fps value to calc frames count
---
src/modules/avformat/producer_avformat.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/src/modules/avformat/producer_avformat.c b/src/modules/avformat/producer_avformat.c
index 9068f08..1e5341c 100644
--- a/src/modules/avformat/producer_avformat.c
+++ b/src/modules/avformat/producer_avformat.c
@@ -575,10 +575,6 @@ static int get_basic_info( producer_avformat self, mlt_profile profile, const ch
AVFormatContext *format = self->video_format;
- // We will treat everything with the producer fps.
- // TODO: make this more flexible.
- double fps = mlt_profile_fps( profile );
-
// Get the duration
if ( !mlt_properties_get_int( properties, "_length_computed" ) )
{
@@ -587,7 +583,9 @@ static int get_basic_info( producer_avformat self, mlt_profile profile, const ch
if ( format->duration != AV_NOPTS_VALUE )
{
// This isn't going to be accurate for all formats
- mlt_position frames = ( mlt_position )( ( ( double )format->duration / ( double )AV_TIME_BASE ) * fps );
+ // We will treat everything with the producer fps.
+ mlt_position frames = ( mlt_position )( int )( format->duration *
+ profile->frame_rate_num / profile->frame_rate_den / AV_TIME_BASE);
mlt_properties_set_position( properties, "out", frames - 1 );
mlt_properties_set_position( properties, "length", frames );
mlt_properties_set_int( properties, "_length_computed", 1 );
--
1.7.7.6
------------------------------------------------------------------------------
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