[FFmpeg-devel] [PATCH] [GSoC 1/6] avformat/abr: Adaptive Bitrate support
Hongcheng Zhong
sj.hc_Zhong at sjtu.edu.cn
Sun Jul 5 14:34:54 EEST 2020
From: spartazhc <spartazhc at gmail.com>
Add abr module for hls/dash.
Signed-off-by: spartazhc <spartazhc at gmail.com>
---
doc/protocols.texi | 7 +
libavformat/Makefile | 1 +
libavformat/abr.c | 282 ++++++++++++++++++++++++++++++++++++++++
libavformat/protocols.c | 1 +
4 files changed, 291 insertions(+)
create mode 100644 libavformat/abr.c
diff --git a/doc/protocols.texi b/doc/protocols.texi
index 644a17963d..fc80209884 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -51,6 +51,13 @@ in microseconds.
A description of the currently available protocols follows.
+ at section abr
+
+Adaptive bitrate sub-protocol work for hls/dash.
+
+The abr protocol takes stream information from hls/dash as input,
+use bandwidth estimation to decide whether to switch or not.
+
@section amqp
Advanced Message Queueing Protocol (AMQP) version 0-9-1 is a broker based
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 26af859a28..3c08289d5e 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -588,6 +588,7 @@ OBJS-$(CONFIG_LIBOPENMPT_DEMUXER) += libopenmpt.o
OBJS-$(CONFIG_VAPOURSYNTH_DEMUXER) += vapoursynth.o
# protocols I/O
+OBJS-$(CONFIG_ABR_PROTOCOL) += abr.o
OBJS-$(CONFIG_ASYNC_PROTOCOL) += async.o
OBJS-$(CONFIG_APPLEHTTP_PROTOCOL) += hlsproto.o
OBJS-$(CONFIG_BLURAY_PROTOCOL) += bluray.o
diff --git a/libavformat/abr.c b/libavformat/abr.c
new file mode 100644
index 0000000000..b7d00efcae
--- /dev/null
+++ b/libavformat/abr.c
@@ -0,0 +1,282 @@
+/*
+ * Adaptive Bitrate Module for HLS / DASH
+ * Copyright (c) 2020 Hongcheng Zhong
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "libavutil/opt.h"
+#include "libavutil/time.h"
+#include "libavutil/avstring.h"
+#include "url.h"
+#include <math.h>
+
+enum ABRFormatType {
+ ABR_TYPE_HLS,
+ ABR_TYPE_DASH
+};
+
+typedef struct variant_bitrate {
+ int value;
+ int index;
+} variant_bitrate;
+
+typedef struct ABRContext {
+ AVClass *class;
+ URLContext *hd;
+ AVDictionary *abr_params;
+ AVDictionary *abr_metadata;
+ enum ABRFormatType format;
+ int cur_pls;
+ int can_switch;
+ int n_variants;
+ variant_bitrate *variants_bitrate;
+ int index;
+ int n_throughputs;
+ float *throughputs;
+ int64_t position;
+} ABRContext;
+
+static float harmonic_mean(int num, float* arr)
+{
+ float tmp = 0;
+
+ if (num <= 0) return 0;
+
+ for (size_t i = 0; i < num; i++) {
+ tmp += 1 / arr[i];
+ }
+
+ return num / tmp;
+}
+
+static int hls_param_parse(ABRContext *c, const char *key, const char *value)
+{
+ if (!av_strcasecmp(key, "cur_pls")) {
+ c->cur_pls = atoi(value);
+ } else if (!av_strcasecmp(key, "can_switch")) {
+ c->can_switch = atoi(value);
+ } else if (!av_strcasecmp(key, "n_variants")) {
+ c->n_variants = atoi(value);
+ c->variants_bitrate = av_mallocz(sizeof(variant_bitrate) * c->n_variants);
+ if (!c->variants_bitrate)
+ return -1;
+ } else if (av_strstart(key, "variant_bitrate", NULL)) {
+ c->variants_bitrate[c->index].value = atoi(value);
+ c->variants_bitrate[c->index].index = c->index;
+ c->index++;
+ } else if (!av_strcasecmp(key, "n_throughputs")) {
+ c->n_throughputs = atoi(value);
+ c->index = 0;
+ if (c->n_throughputs > 0) {
+ c->throughputs = av_malloc(sizeof(float) * c->n_throughputs);
+ if (!c->throughputs)
+ return -1;
+ }
+ } else if (av_strstart(key, "throughputs", NULL))
+ c->throughputs[c->index++] = atof(value);
+ return 0;
+}
+
+static int dash_param_parse(ABRContext *c, const char *key, const char *value)
+{
+ return 0;
+}
+
+static int abr_param_parse(ABRContext *c, enum ABRFormatType type, const char *key, const char *value)
+{
+ if (type == ABR_TYPE_HLS) {
+ hls_param_parse(c, key, value);
+ } else if (type == ABR_TYPE_DASH) {
+ dash_param_parse(c, key, value);
+ }
+ return 0;
+}
+
+static int compare_vb(const void *a, const void *b)
+{
+ variant_bitrate *a1 = (variant_bitrate *)a;
+ variant_bitrate *a2 = (variant_bitrate *)b;
+ return (*a2).value - (*a1).value;
+}
+
+static int abr_rule(ABRContext *c, float bw_estimate)
+{
+ int ret = -1;
+
+ if (c->n_throughputs > 6) {
+ if (bw_estimate < c->variants_bitrate[c->cur_pls].value / 1000 * 1.2 &&
+ bw_estimate > c->variants_bitrate[c->cur_pls].value / 1000 * 0.8)
+ return -1;
+ qsort(c->variants_bitrate, c->n_variants, sizeof(variant_bitrate), compare_vb);
+ for (int i = 0; i < c->n_variants; i++) {
+ if (bw_estimate > c->variants_bitrate[i].value / 1000) {
+ ret = i;
+ break;
+ }
+ }
+ }
+ if (ret == c->cur_pls)
+ ret = -1;
+ av_log(c, AV_LOG_VERBOSE, "[switch] bwe=%.2fkbps, cur=%d, switch=%d\n", bw_estimate, c->cur_pls, ret);
+ return ret;
+}
+
+static int abr_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
+{
+ const char *nested_url;
+ uint64_t start, end;
+ float bw_estimation;
+ int switch_request = -1;
+ int ret = 0;
+ ABRContext *c = h->priv_data;
+
+ if (!av_strstart(uri, "abr+", &nested_url) &&
+ !av_strstart(uri, "abr:", &nested_url)) {
+ av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
+ ret = AVERROR(EINVAL);
+ goto err;
+ }
+
+ {
+ AVDictionaryEntry *en = NULL;
+ en = av_dict_get(c->abr_params, "", en, AV_DICT_IGNORE_SUFFIX);
+ if (!en)
+ return -1;
+ if (!av_strcasecmp(en->key, "format")) {
+ if (!av_strcasecmp(en->value, "hls")) {
+ c->format = ABR_TYPE_HLS;
+ } else if (!av_strcasecmp(en->value, "dash")) {
+ c->format = ABR_TYPE_DASH;
+ }
+ av_log(h, AV_LOG_VERBOSE, "%s is using ABR\n", en->value);
+ }
+
+ while (en = av_dict_get(c->abr_params, "", en, AV_DICT_IGNORE_SUFFIX)) {
+ if (abr_param_parse(c, c->format, en->key, en->value) < 0)
+ av_log(h, AV_LOG_WARNING,
+ "Error parsing option '%s = %s'.\n",
+ en->key, en->value);
+ }
+ }
+
+ start = av_gettime();
+ if ((ret = ffurl_open_whitelist(&c->hd, nested_url, flags,
+ &h->interrupt_callback, options,
+ h->protocol_whitelist, h->protocol_blacklist, h)) < 0) {
+ av_log(h, AV_LOG_ERROR, "Unable to open resource: %s\n", nested_url);
+ goto err;
+ }
+ end = av_gettime();
+
+ bw_estimation = harmonic_mean(c->n_throughputs, c->throughputs);
+
+ if (c->can_switch == 1)
+ switch_request = abr_rule(c, bw_estimation);
+
+ av_dict_set_int(&c->abr_metadata, "download_time", (end - start), 0);
+ av_dict_set_int(&c->abr_metadata, "switch_request", switch_request, 0);
+
+err:
+ return ret;
+}
+
+
+static int abr_read(URLContext *h, uint8_t *buf, int size)
+{
+ ABRContext *c = h->priv_data;
+
+ return ffurl_read(c->hd, buf, size);
+}
+
+static int64_t abr_seek(URLContext *h, int64_t pos, int whence)
+{
+ ABRContext *c = h->priv_data;
+ int64_t newpos;
+
+ switch (whence) {
+ case SEEK_SET:
+ break;
+ case SEEK_CUR:
+ pos = pos + c->position;
+ break;
+ case SEEK_END: {
+ int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE );
+ if (newpos < 0) {
+ av_log(h, AV_LOG_ERROR,
+ "ABR: seek_end - can't get file size (pos=%lld)\r\n", (long long int)pos);
+ return newpos;
+ }
+ pos = newpos - pos;
+ }
+ break;
+ case AVSEEK_SIZE: {
+ int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE );
+ return newpos;
+ }
+ break;
+ default:
+ av_log(h, AV_LOG_ERROR,
+ "ABR: no support for seek where 'whence' is %d\r\n", whence);
+ return AVERROR(EINVAL);
+ }
+
+ newpos = ffurl_seek( c->hd, c->position, SEEK_SET );
+ if (newpos < 0) {
+ av_log(h, AV_LOG_ERROR,
+ "ABR: nested protocol no support for seek or seek failed\n");
+ return newpos;
+ }
+ return c->position;
+}
+
+static int abr_close(URLContext *h)
+{
+ ABRContext *c = h->priv_data;
+ int ret = 0;
+
+ ffurl_closep(&c->hd);
+ av_free(c->variants_bitrate);
+ av_free(c->throughputs);
+ return ret;
+}
+
+#define OFFSET(x) offsetof(ABRContext, x)
+#define D AV_OPT_FLAG_DECODING_PARAM
+static const AVOption options[] = {
+ { "abr-params", "Informations ABR needed, using a :-separated list of key=value parameters", OFFSET(abr_params), AV_OPT_TYPE_DICT, { 0 }, 0, 0, D },
+ { "abr-metadata", "Metadata return from abr, including switch signal and network bandwidth", OFFSET(abr_metadata), AV_OPT_TYPE_DICT, { 0 }, 0, 0, D },
+ { NULL }
+};
+
+static const AVClass abr_class = {
+ .class_name = "abr",
+ .item_name = av_default_item_name,
+ .option = options,
+ .version = LIBAVUTIL_VERSION_INT,
+};
+
+const URLProtocol ff_abr_protocol = {
+ .name = "abr",
+ .url_open2 = abr_open,
+ .url_read = abr_read,
+ .url_seek = abr_seek,
+ .url_close = abr_close,
+ .priv_data_size = sizeof(ABRContext),
+ .priv_data_class = &abr_class,
+};
diff --git a/libavformat/protocols.c b/libavformat/protocols.c
index 7df18fbb3b..16c844c914 100644
--- a/libavformat/protocols.c
+++ b/libavformat/protocols.c
@@ -23,6 +23,7 @@
#include "url.h"
+extern const URLProtocol ff_abr_protocol;
extern const URLProtocol ff_async_protocol;
extern const URLProtocol ff_bluray_protocol;
extern const URLProtocol ff_cache_protocol;
--
2.27.0
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