[FFmpeg-devel] [PATCH] [GSoC v3 1/7] avformat/abr: Adaptive Bitrate support
Steven Liu
lq at chinaffmpeg.org
Thu Sep 3 17:59:14 EEST 2020
> 在 2020年8月23日，20:23，Hongcheng Zhong <sj.hc_zhong at sjtu.edu.cn> 写道：
>
> From: spartazhc <spartazhc at gmail.com>
>
> Add abr module for hls/dash.
>
> Signed-off-by: spartazhc <spartazhc at gmail.com>
>
> v1 fixed:
> 1. add an "ff" prefix to the protocol name to mark it internal.
> 2. use 1.2f for float constant 1.2.
> 3. simplify abr_seek for we just need AVSEEK_SIZE only.
>
> v2 fixed:
> 1. fix error return
> 2. simplify abr_seek
>
> v3 fixed:
> 1. rewrite hls_param_parse function
> 2. fix error code return
> 3. use unsigned type and const prefix
> 4. fix documentation
> 5. fix abr_rule
> 6. rename cur_pls to cur_var
> 7. add type input and output
> ---
> doc/protocols.texi | 7 ++
> libavformat/Makefile | 1 +
> libavformat/ffabr.c | 271 ++++++++++++++++++++++++++++++++++++++++
> libavformat/protocols.c | 1 +
> 4 files changed, 280 insertions(+)
> create mode 100644 libavformat/ffabr.c
>
> diff --git a/doc/protocols.texi b/doc/protocols.texi
> index 7b3df96fda..e31de80ab6 100644
> --- a/doc/protocols.texi
> +++ b/doc/protocols.texi
> @@ -232,6 +232,13 @@ For example, to convert a GIF file given inline with @command{ffmpeg}:
> ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png
> @end example
>
> + at section ffabr
> +
> +Adaptive bitrate sub-protocol work for hls/dash, ffabr is internal.
> +
> +The ffabr protocol takes stream information from hls/dash as input,
> +use bandwidth estimation to decide whether to switch or not.
> +
> @section file
>
> File access protocol.
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index cbb33fe37c..68b004eee0 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -598,6 +598,7 @@ OBJS-$(CONFIG_CACHE_PROTOCOL) += cache.o
> OBJS-$(CONFIG_CONCAT_PROTOCOL) += concat.o
> OBJS-$(CONFIG_CRYPTO_PROTOCOL) += crypto.o
> OBJS-$(CONFIG_DATA_PROTOCOL) += data_uri.o
> +OBJS-$(CONFIG_FFABR_PROTOCOL) += ffabr.o
> OBJS-$(CONFIG_FFRTMPCRYPT_PROTOCOL) += rtmpcrypt.o rtmpdigest.o rtmpdh.o
> OBJS-$(CONFIG_FFRTMPHTTP_PROTOCOL) += rtmphttp.o
> OBJS-$(CONFIG_FILE_PROTOCOL) += file.o
> diff --git a/libavformat/ffabr.c b/libavformat/ffabr.c
> new file mode 100644
> index 0000000000..1785ef5643
> --- /dev/null
> +++ b/libavformat/ffabr.c
> @@ -0,0 +1,271 @@
> +/*
> + * Adaptive Bitrate Module for HLS / DASH
> + * Copyright (c) 2020
> + *
> + * 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 <math.h>
> +#include "avformat.h"
> +#include "libavutil/avassert.h"
> +#include "libavutil/avstring.h"
> +#include "libavutil/common.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/time.h"
> +#include "url.h"
> +
> +#define ABR_NOT_SWITCH -1
> +
> +enum ABRFormatType {
> + ABR_TYPE_HLS,
> + ABR_TYPE_DASH
> +};
> +
> +typedef struct Variant {
> + uint32_t bitrate;
> + size_t index;
> +} variant;
> +
> +typedef struct ABRContext {
> + const AVClass *class;
> + URLContext *hd;
> + AVDictionary *abr_params;
> + AVDictionary *abr_metadata;
> + enum ABRFormatType format;
> + uint8_t cur_var;
> + uint8_t type;
> + int8_t can_switch;
> + size_t n_variants;
> + variant *variants;
> + size_t n_throughputs;
> + float *throughputs;
> +} ABRContext;
> +
> +static float harmonic_mean(const float *arr, size_t num)
> +{
> + float tmp = 0;
> +
> + if (!num) 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 AVDictionaryEntry *entry)
> +{
> + AVDictionaryEntry *en;
> + size_t index;
> + char key_tmp[20];
> +
> +
> + en = av_dict_get(c->abr_params, "cur_var", entry, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + c->cur_var = strtol(en->value, NULL, 10);
I saw you define it with uint8_t, maybe this will overflow if use long strtol
or define it int64_t and strtoll here?
> + }
> + en = av_dict_get(c->abr_params, "type", entry, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + c->type = strtol(en->value, NULL, 10);
I saw you define it with uint8_t, maybe this will overflow if use long strtol
> + }
> + en = av_dict_get(c->abr_params, "can_switch", entry, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + c->can_switch = strtol(en->value, NULL, 10);
I saw you define it with int8_t, maybe this will overflow if use long strtol
> + }
> + en = av_dict_get(c->abr_params, "n_variants", entry, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + c->n_variants = strtol(en->value, NULL, 10);
> + c->variants = av_mallocz(sizeof(variant) * c->n_variants);
> + if (!c->variants)
> + return AVERROR(ENOMEM);
> + index = 0;
> + snprintf(key_tmp, sizeof(key_tmp), "variant_bitrate%ld", index);
> + while ((en = av_dict_get(c->abr_params, key_tmp, entry, AV_DICT_IGNORE_SUFFIX))
> + && index < c->n_variants) {
> + c->variants[index].bitrate = strtol(en->value, NULL, 10);
> + c->variants[index].index = index;
> + index++;
> + snprintf(key_tmp, sizeof(key_tmp), "variant_bitrate%ld", index);
> + }
> + }
> + en = av_dict_get(c->abr_params, "n_throughputs", entry, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + c->n_throughputs = strtol(en->value, NULL, 10);
> + if (!c->n_throughputs)
> + return 0;
> + c->throughputs = av_malloc(sizeof(float) * c->n_throughputs);
> + if (!c->throughputs)
> + return AVERROR(ENOMEM);
maybe will memleak if return here, because you call av_mallocz and above for the c->variants.
what about use goto fail: and free them in fail label at the end of this function?
> + index = 0;
> + snprintf(key_tmp, sizeof(key_tmp), "throughputs%ld", index);
> + while ((en = av_dict_get(c->abr_params, key_tmp, entry, AV_DICT_IGNORE_SUFFIX))
> + && index < c->n_throughputs) {
> + c->throughputs[index++] = strtol(en->value, NULL, 10);
> + snprintf(key_tmp, sizeof(key_tmp), "throughputs%ld", index);
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int abr_param_parse(ABRContext *c, enum ABRFormatType type, const AVDictionaryEntry *en)
> +{
> + int ret;
> + if (type == ABR_TYPE_HLS) {
> + ret = hls_param_parse(c, en);
> + }
> + return ret;
> +}
> +
> +static int compare_vb(const void *a, const void *b)
> +{
> + return FFDIFFSIGN((*(const variant *)b).bitrate, (*(const variant *)a).bitrate);
> +}
> +
> +static int abr_rule(URLContext *h, float bw_estimate)
> +{
> + int ret = ABR_NOT_SWITCH;
> + ABRContext *c = h->priv_data;
> +
> + if (bw_estimate < c->variants[c->cur_var].bitrate / 1000 * 1.2f &&
> + bw_estimate > c->variants[c->cur_var].bitrate / 1000 * 0.8f)
> + return ABR_NOT_SWITCH;
> + qsort(c->variants, c->n_variants, sizeof(variant), compare_vb);
> + for (int i = 0; i < c->n_variants; i++) {
> + if (bw_estimate > c->variants[i].bitrate / 1000) {
maybe you want 1000.0 for float?
> + ret = c->variants[i].index;
> + break;
> + }
> + }
> + if (ret == ABR_NOT_SWITCH)
> + ret = c->variants[c->n_variants - 1].index;
> + else if (ret == c->cur_var)
> + ret = ABR_NOT_SWITCH;
> +
> + av_log(h, AV_LOG_VERBOSE, "[switch] bwe=%.2fkbps, cur=%d, switch=%d\n", bw_estimate, c->cur_var, ret);
what about use AV_LOG_DEBUG?
> + return ret;
> +}
> +
> +static int abr_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
> +{
> + const char *nested_url;
> + int64_t start, end;
> + float bw_estimation;
> + int switch_request = ABR_NOT_SWITCH;
> + int ret = 0;
> + ABRContext *c = h->priv_data;
> + AVDictionaryEntry *en = NULL;
> +
> + if (!av_strstart(uri, "ffabr+", &nested_url) &&
> + !av_strstart(uri, "ffabr:", &nested_url)) {
> + av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
> + return AVERROR(EINVAL);
> + }
> +
> + en = av_dict_get(c->abr_params, "format", en, AV_DICT_IGNORE_SUFFIX);
> + if (en) {
> + 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);
> + } else {
> + return AVERROR(EINVAL);
> + }
> +
> + if (ret = abr_param_parse(c, c->format, en) < 0) {
> + av_log(h, AV_LOG_ERROR,"Error parsing abr params.\n");
> + return ret;
> + }
> +
> + 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);
> + return ret;
> + }
> + end = av_gettime();
> +
> + bw_estimation = harmonic_mean(c->throughputs, c->n_throughputs);
> +
> + if (c->can_switch == 1)
> + switch_request = abr_rule(h, 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);
> + av_dict_set_int(&c->abr_metadata, "type", c->type, 0);
> +
> + 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;
> +
> + if (whence == AVSEEK_SIZE) {
> + return ffurl_seek(c->hd, pos, AVSEEK_SIZE);
> + } else {
> + return AVERROR(errno);
> + }
> +}
> +
> +static int abr_close(URLContext *h)
> +{
> + ABRContext *c = h->priv_data;
> + int ret = 0;
> +
> + ffurl_closep(&c->hd);
> + av_free(c->variants);
> + av_free(c->throughputs);
> + return ret;
> +}
> +
> +#define OFFSET(x) offsetof(ABRContext, x)
> +#define D AV_OPT_FLAG_DECODING_PARAM
> +static const AVOption ffabr_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 ffabr_class = {
> + .class_name = "ffabr",
> + .item_name = av_default_item_name,
> + .option = ffabr_options,
> + .version = LIBAVUTIL_VERSION_INT,
> +};
> +
> +const URLProtocol ff_ffabr_protocol = {
> + .name = "ffabr",
> + .url_open2 = abr_open,
> + .url_read = abr_read,
> + .url_seek = abr_seek,
> + .url_close = abr_close,
> + .priv_data_size = sizeof(ABRContext),
> + .priv_data_class = &ffabr_class,
> +};
> diff --git a/libavformat/protocols.c b/libavformat/protocols.c
> index 7df18fbb3b..1d6af8e380 100644
> --- a/libavformat/protocols.c
> +++ b/libavformat/protocols.c
> @@ -29,6 +29,7 @@ extern const URLProtocol ff_cache_protocol;
> extern const URLProtocol ff_concat_protocol;
> extern const URLProtocol ff_crypto_protocol;
> extern const URLProtocol ff_data_protocol;
> +extern const URLProtocol ff_ffabr_protocol;
> extern const URLProtocol ff_ffrtmpcrypt_protocol;
> extern const URLProtocol ff_ffrtmphttp_protocol;
> extern const URLProtocol ff_file_protocol;
> --
> 2.28.0
>
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Thanks
Steven
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