[FFmpeg-devel] [PATCH] avformat/libsrt: Change latency option to milliseconds

Limin Wang lance.lmwang at gmail.com
Wed Apr 8 04:45:57 EEST 2020


On Wed, Apr 08, 2020 at 02:16:23AM +0200, pkv wrote:
> Hi
> 
> Le 08/04/2020 à 12:33 am, Limin Wang a écrit :
> >On Tue, Apr 07, 2020 at 08:25:44PM +0200, pkv wrote:
> >>Hi
> >>
> >>new patch for latency option following the comments from N. George.
> >I recall I had submit a patchset for related option incliding latency.
> >https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200331140808.8839-2-lance.lmwang@gmail.com/
> 
> hadn't spotted it; why was it not merged ?
> 
> 
> >
> >Why I haven't change to use AV_OPT_TYPE_DURATION, for the latency can
> >be used in format srt://xxxx:port?latency=?, it's in unit of ms,
> >in addition, AV_OPT_TYPE_DURATION is in unit of second default, it'll
> >break the old user.
> i tested with ffmpeg.exe; the change to
> 
> AV_OPT_TYPE_DURATION
> 
> didn't seem to break anything.
> 
> The default is still set to whatever the libsrt API has set (120 ms
> for transtype=live).
> 
> Can you produce code broken by that change ?

What's your command line? 
I recall If use AV_OPT_TYPE_DURATION for option, the default is in unit of second if your
don't add suffix of ms, us. However the old is us, so it'll cause old user
setting broken.


> 
> Regards
> 
> 
> >
> >>=====
> >>
> >>Updated protocol doc for srt to specify the unit of various latency options.
> >>Furthermore the type of the latency options is changed to
> >>AV_OPT_TYPE_DURATION
> >>(following comment from N. George).
> >>
> >>The microsecond unit has caused confusion for both FFmpeg and
> >>obs-studio users:
> >>- https://github.com/Haivision/srt/issues/1223
> >>
> >>- https://obsproject.com/mantis/view.php?id=1617
> >>
> >>=====
> >>
> >>Regards
> >>
> >> From 1dd49812553f44bc5f1ed60660a2365d6a036c97 Mon Sep 17 00:00:00 2001
> >>From: pkv <pkv at obsproject.com>
> >>Date: Tue, 7 Apr 2020 18:08:22 +0200
> >>Subject: [PATCH] avformat/libsrt: Document latency options unit
> >>
> >>Updated protocol doc for srt to specify the unit of various latency options.
> >>Furthermore the type of the latency options is changed to AV_OPT_TYPE_DURATION
> >>(following comment from N. George).
> >>
> >>The microsecond unit has caused confusion for both FFmpeg and obs-studio users:
> >>- https://github.com/Haivision/srt/issues/1223
> >>
> >>- https://obsproject.com/mantis/view.php?id=1617
> >>---
> >>  doc/protocols.texi   | 6 +++---
> >>  libavformat/libsrt.c | 6 +++---
> >>  2 files changed, 6 insertions(+), 6 deletions(-)
> >>
> >>diff --git a/doc/protocols.texi b/doc/protocols.texi
> >>index e510019f2d..ebf9dec529 100644
> >>--- a/doc/protocols.texi
> >>+++ b/doc/protocols.texi
> >>@@ -1286,8 +1286,8 @@ IP Type of Service. Applies to sender only. Default value is 0xB8.
> >>  @item ipttl=@var{ttl}
> >>  IP Time To Live. Applies to sender only. Default value is 64.
> >>- at item latency
> >>-Timestamp-based Packet Delivery Delay.
> >>+ at item latency=@var{microseconds}
> >>+Timestamp-based Packet Delivery Delay in microseconds.
> >>  Used to absorb bursts of missed packet retransmissions.
> >>  This flag sets both @option{rcvlatency} and @option{peerlatency}
> >>  to the same value. Note that prior to version 1.3.0
> >>@@ -1389,7 +1389,7 @@ Not required on receiver (set to 0),
> >>  key size obtained from sender in HaiCrypt handshake.
> >>  Default value is 0.
> >>- at item rcvlatency
> >>+ at item rcvlatency at var{microseconds}
> >>  The time that should elapse since the moment when the
> >>  packet was sent and the moment when it's delivered to
> >>  the receiver application in the receiving function.
> >>diff --git a/libavformat/libsrt.c b/libavformat/libsrt.c
> >>index 2d6fc4b7e7..5c61f9e0d7 100644
> >>--- a/libavformat/libsrt.c
> >>+++ b/libavformat/libsrt.c
> >>@@ -118,10 +118,10 @@ static const AVOption libsrt_options[] = {
> >>      { "iptos",          "IP Type of Service",                                                   OFFSET(iptos),            AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 255,       .flags = D|E },
> >>      { "inputbw",        "Estimated input stream rate",                                          OFFSET(inputbw),          AV_OPT_TYPE_INT64,    { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>      { "oheadbw",        "MaxBW ceiling based on % over input stream rate",                      OFFSET(oheadbw),          AV_OPT_TYPE_INT,      { .i64 = -1 }, -1, 100,       .flags = D|E },
> >>-    { "latency",        "receiver delay to absorb bursts of missed packet retransmissions",     OFFSET(latency),          AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>+    { "latency",        "receiver delay to absorb bursts of missed packet retransmissions",     OFFSET(latency),          AV_OPT_TYPE_DURATION, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>      { "tsbpddelay",     "deprecated, same effect as latency option",                            OFFSET(latency),          AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>-    { "rcvlatency",     "receive latency",                                                      OFFSET(rcvlatency),       AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>-    { "peerlatency",    "peer latency",                                                         OFFSET(peerlatency),      AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>+    { "rcvlatency",     "receive latency",                                                      OFFSET(rcvlatency),       AV_OPT_TYPE_DURATION, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>+    { "peerlatency",    "peer latency",                                                         OFFSET(peerlatency),      AV_OPT_TYPE_DURATION, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>      { "tlpktdrop",      "Enable receiver pkt drop",                                             OFFSET(tlpktdrop),        AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
> >>      { "nakreport",      "Enable receiver to send periodic NAK reports",                         OFFSET(nakreport),        AV_OPT_TYPE_BOOL,     { .i64 = -1 }, -1, 1,         .flags = D|E },
> >>      { "connect_timeout", "Connect timeout. Caller default: 3000, rendezvous (x 10)",            OFFSET(connect_timeout),  AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, .flags = D|E },
> >>-- 
> >>2.24.1.windows.2
> >>
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-- 
Thanks,
Limin Wang


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