[FFmpeg-devel] [PATCH v2 3/5] avformat/hls: add http_persistent option

Anssi Hannula anssi.hannula at iki.fi
Sun Dec 17 23:13:02 EET 2017


Aman Gupta kirjoitti 2017-12-17 22:41:
> On Sun, Dec 17, 2017 at 12:34 PM Anssi Hannula <anssi.hannula at iki.fi> 
> wrote:
> 
>> Hi!
>> 
>> Aman Gupta kirjoitti 2017-12-13 02:35:
>> > From: Aman Gupta <aman at tmm1.net>
>> >
>> > This teaches the HLS demuxer to use the HTTP protocols
>> > multiple_requests=1 option, to take advantage of "Connection:
>> > Keep-Alive" when downloading playlists and segments from the HLS
>> > server.
>> >
>> > With the new option, you can avoid TCP connection and TLS negotiation
>> > overhead, which is particularly beneficial when streaming via a
>> > high-latency internet connection.
>> >
>> > Similar to the http_persistent option recently implemented in hlsenc.c
>> 
>> Why is this implemented as an option instead of simply being always 
>> used
>> by the demuxer?
> 
> 
> I have no strong feeling on this either way. I've tested the new option
> against a few different HLS servers and would be comfortable enabling 
> it by
> default. I do think it's worth keeping as an option in case someone 
> wants
> to turn it off for whatever reason.

OK. The only other demuxer that reuses HTTP connections seems to be 
rtmphttp, and it does not have an option.
I think I'd prefer no option here as well unless a use case is known, 
but I'm not too strongly against it so I guess it could stay (but 
default to true).

Does anyone else have any thoughts?


Also, what happens if the hostname in the URI varies, does it properly 
open a new connection then?

> 
>> 
>> > ---
>> >  doc/demuxers.texi |  3 +++
>> >  libavformat/hls.c | 68
>> > +++++++++++++++++++++++++++++++++++++++++++++++++++----
>> >  2 files changed, 67 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/doc/demuxers.texi b/doc/demuxers.texi
>> > index 73dc0feec1..18ff7101ac 100644
>> > --- a/doc/demuxers.texi
>> > +++ b/doc/demuxers.texi
>> > @@ -316,6 +316,9 @@ segment index to start live streams at (negative
>> > values are from the end).
>> >  @item max_reload
>> >  Maximum number of times a insufficient list is attempted to be
>> > reloaded.
>> >  Default value is 1000.
>> > +
>> > + at item http_persistent
>> > +Use persistent HTTP connections. Applicable only for HTTP streams.
>> >  @end table
>> >
>> >  @section image2
>> > diff --git a/libavformat/hls.c b/libavformat/hls.c
>> > index ab6ff187a6..5c1895c180 100644
>> > --- a/libavformat/hls.c
>> > +++ b/libavformat/hls.c
>> > @@ -26,6 +26,7 @@
>> >   * http://tools.ietf.org/html/draft-pantos-http-live-streaming
>> >   */
>> >
>> > +#include "libavformat/http.h"
>> >  #include "libavutil/avstring.h"
>> >  #include "libavutil/avassert.h"
>> >  #include "libavutil/intreadwrite.h"
>> > @@ -94,6 +95,7 @@ struct playlist {
>> >      AVIOContext pb;
>> >      uint8_t* read_buffer;
>> >      AVIOContext *input;
>> > +    int input_read_done;
>> >      AVFormatContext *parent;
>> >      int index;
>> >      AVFormatContext *ctx;
>> > @@ -206,6 +208,8 @@ typedef struct HLSContext {
>> >      int strict_std_compliance;
>> >      char *allowed_extensions;
>> >      int max_reload;
>> > +    int http_persistent;
>> > +    AVIOContext *playlist_pb;
>> >  } HLSContext;
>> >
>> >  static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
>> > @@ -256,6 +260,7 @@ static void free_playlist_list(HLSContext *c)
>> >          av_freep(&pls->pb.buffer);
>> >          if (pls->input)
>> >              ff_format_io_close(c->ctx, &pls->input);
>> > +        pls->input_read_done = 0;
>> >          if (pls->ctx) {
>> >              pls->ctx->pb = NULL;
>> >              avformat_close_input(&pls->ctx);
>> > @@ -640,7 +645,24 @@ static int open_url(AVFormatContext *s,
>> > AVIOContext **pb, const char *url,
>> >      else if (strcmp(proto_name, "file") || !strncmp(url, "file,", 5))
>> >          return AVERROR_INVALIDDATA;
>> >
>> > -    ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
>> > +    if (c->http_persistent && *pb && av_strstart(proto_name, "http",
>> > NULL)) {
>> > +        URLContext *uc = ffio_geturlcontext(*pb);
>> > +        av_assert0(uc);
>> > +        (*pb)->eof_reached = 0;
>> > +        ret = ff_http_do_new_request(uc, url);
>> > +        if (ret == AVERROR_EXIT) {
>> > +            ff_format_io_close(c->ctx, &c->playlist_pb);
>> > +            return ret;
>> > +        } else if (ret < 0) {
>> > +            av_log(s, AV_LOG_WARNING,
>> > +                "keepalive request failed for '%s', retrying with new
>> > connection: %s\n",
>> > +                url, av_err2str(ret));
>> > +            ff_format_io_close(c->ctx, pb);
>> > +            ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
>> > +        }
>> > +    } else {
>> > +        ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
>> > +    }
>> >      if (ret >= 0) {
>> >          // update cookies on http response with setcookies.
>> >          char *new_cookies = NULL;
>> > @@ -683,10 +705,27 @@ static int parse_playlist(HLSContext *c, const
>> > char *url,
>> >      char tmp_str[MAX_URL_SIZE];
>> >      struct segment *cur_init_section = NULL;
>> >
>> > +    if (!in && c->http_persistent && c->playlist_pb) {
>> > +        in = c->playlist_pb;
>> > +        URLContext *uc = ffio_geturlcontext(in);
>> > +        av_assert0(uc);
>> > +        in->eof_reached = 0;
>> > +        ret = ff_http_do_new_request(uc, url);
>> > +        if (ret == AVERROR_EXIT) {
>> > +            ff_format_io_close(c->ctx, &c->playlist_pb);
>> > +            return ret;
>> > +        } else if (ret < 0) {
>> > +            av_log(c->ctx, AV_LOG_WARNING,
>> > +                "keepalive request failed for '%s', retrying with new
>> > connection: %s\n",
>> > +                url, av_err2str(ret));
>> > +            ff_format_io_close(c->ctx, &c->playlist_pb);
>> > +            in = NULL;
>> > +        }
>> > +    }
>> > +
>> 
>> The above code seems duplicated, please put it in a common function.
> 
> 
> Sure, will do.
> 
> Thanks for reviewing!
> 
> 
>> 
>> 
>> [..]
>> --
>> Anssi Hannula
>> 
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-- 
Anssi Hannula


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