[FFmpeg-devel] [PATCH 3/3] avformat/hls: add http_keepalive option
Moritz Barsnick
barsnick at gmx.net
Thu Oct 5 17:32:00 EEST 2017
On Wed, Oct 04, 2017 at 15:03:34 -0700, Aman Gupta wrote:
> 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.
Nice.
Quick test: A random akamaihd.net HLS stream (they provide great
bandwidth) with quite small segments (~10s per segment) goes from 14.8x
to 16x. The overhead reduction seems significant, and this isn't even
https segments.
Issue: The hls demuxer now inconsistently no longer reports each opened
URL, only the first one. (Reporting of these at default log-level was
only recently added though.)
>
> 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.
> ---
> libavformat/hls.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 47 insertions(+), 4 deletions(-)
>
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index 786934af03..bf90582755 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_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_keepalive;
> + AVIOContext *playlist_pb;
> } HLSContext;
>
> static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
> @@ -640,7 +644,17 @@ 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_keepalive && *pb && av_strstart(proto_name, "http", NULL)) {
> + URLContext *uc = (URLContext *)av_opt_child_next(*pb, NULL);
> + (*pb)->eof_reached = 0;
> + ret = ff_http_do_new_request(uc, url);
> + if (ret < 0) {
> + 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 +697,20 @@ 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_keepalive && c->playlist_pb) {
> + in = c->playlist_pb;
> + URLContext *uc = (URLContext *)av_opt_child_next(in, NULL);
> + in->eof_reached = 0;
> + ret = ff_http_do_new_request(uc, url);
> + if (ret < 0) {
> + ff_format_io_close(c->ctx, &c->playlist_pb);
> + in = NULL;
> + }
> + }
> +
> if (!in) {
> #if 1
> AVDictionary *opts = NULL;
> - close_in = 1;
> /* Some HLS servers don't like being sent the range header */
> av_dict_set(&opts, "seekable", "0", 0);
>
> @@ -696,10 +720,18 @@ static int parse_playlist(HLSContext *c, const char *url,
> av_dict_set(&opts, "headers", c->headers, 0);
> av_dict_set(&opts, "http_proxy", c->http_proxy, 0);
>
> + if (c->http_keepalive)
> + av_dict_set(&opts, "multiple_requests", "1", 0);
> +
> ret = c->ctx->io_open(c->ctx, &in, url, AVIO_FLAG_READ, &opts);
> av_dict_free(&opts);
> if (ret < 0)
> return ret;
> +
> + if (c->http_keepalive)
> + c->playlist_pb = in;
> + else
> + close_in = 1;
> #else
> ret = open_in(c, &in, url);
> if (ret < 0)
> @@ -1111,6 +1143,9 @@ static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg)
> av_dict_set(&opts, "http_proxy", c->http_proxy, 0);
> av_dict_set(&opts, "seekable", "0", 0);
>
> + if (c->http_keepalive)
> + av_dict_set(&opts, "multiple_requests", "1", 0);
> +
> if (seg->size >= 0) {
> /* try to restrict the HTTP request to the part we want
> * (if this is in fact a HTTP request) */
> @@ -1270,7 +1305,7 @@ restart:
> if (!v->needed)
> return AVERROR_EOF;
>
> - if (!v->input) {
> + if (!v->input || (c->http_keepalive && v->input_done)) {
> int64_t reload_interval;
> struct segment *seg;
>
> @@ -1329,6 +1364,7 @@ reload:
> goto reload;
> }
>
> + v->input_done = 0;
> seg = current_segment(v);
>
> /* load/update Media Initialization Section, if any */
> @@ -1366,7 +1402,11 @@ reload:
>
> return ret;
> }
> - ff_format_io_close(v->parent, &v->input);
> + if (c->http_keepalive) {
> + v->input_done = 1;
> + } else {
> + ff_format_io_close(v->parent, &v->input);
> + }
> v->cur_seq_no++;
>
> c->cur_seq_no = v->cur_seq_no;
> @@ -1627,6 +1667,7 @@ static int hls_close(AVFormatContext *s)
> free_rendition_list(c);
>
> av_dict_free(&c->avio_opts);
> + ff_format_io_close(c->ctx, &c->playlist_pb);
>
> return 0;
> }
> @@ -2157,6 +2198,8 @@ static const AVOption hls_options[] = {
> INT_MIN, INT_MAX, FLAGS},
> {"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
> OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
> + {"http_keepalive", "re-use http connections when reloading playlists and fetching new segments",
> + OFFSET(http_keepalive), AV_OPT_TYPE_BOOL, {.i64 = 0}, INT_MIN, 1, FLAGS},
> {NULL}
> };
>
> --
> 2.13.5 (Apple Git-94)
>
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