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

pkv pkv at obsproject.com
Wed Apr 8 10:34:45 EEST 2020


Le 08/04/2020 à 3:45 am, Limin Wang a écrit :
> 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.
>
Ok I get your point.

here are the commands I tested with:

ffmpeg.exe -re -i source.mp4 -c copy -f mpegts srt:://dest:port

and

ffmpeg.exe -re -i source.mp4 -c copy -f mpegts 
srt:://dest:port?latency=400000

These two don't break anything.

But indeed

ffmpeg.exe -re -i source.mp4 -c copy -latency=400000 -f mpegts 
srt:://dest:port

is breaking stuff.

I'll revert the change suggested by N. George in that case.

Thanks.

Regards



>> 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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