Add Apple HTTP Live Streaming protocol handler

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

doc/general.texi

@@ -707,6 +707,7 @@ performance on systems without hardware floating point support).
 
 @multitable @columnfractions .4 .1
 @item Name         @tab Support
+@item Apple HTTP Live Streaming @tab X
 @item file         @tab X
 @item Gopher       @tab X
 @item HTTP         @tab X

libavformat/Makefile

@@ -308,6 +308,7 @@ OBJS-$(CONFIG_LIBNUT_MUXER)              += libnut.o riff.o
 # protocols I/O
 OBJS+= avio.o aviobuf.o
 
+OBJS-$(CONFIG_APPLEHTTP_PROTOCOL)        += applehttpproto.o
 OBJS-$(CONFIG_CONCAT_PROTOCOL)           += concat.o
 OBJS-$(CONFIG_FILE_PROTOCOL)             += file.o
 OBJS-$(CONFIG_GOPHER_PROTOCOL)           += gopher.o

libavformat/allformats.c

@@ -229,6 +229,7 @@ void av_register_all(void)
     REGISTER_MUXDEMUX (LIBNUT, libnut);
 
     /* protocols */
+    REGISTER_PROTOCOL (APPLEHTTP, applehttp);
     REGISTER_PROTOCOL (CONCAT, concat);
     REGISTER_PROTOCOL (FILE, file);
     REGISTER_PROTOCOL (GOPHER, gopher);

libavformat/applehttpproto.c

+/*
+ * Apple HTTP Live Streaming Protocol Handler
+ * Copyright (c) 2010 Martin Storsjo
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Apple HTTP Live Streaming Protocol Handler
+ * http://tools.ietf.org/html/draft-pantos-http-live-streaming
+ */
+
+#define _XOPEN_SOURCE 600
+#include "libavutil/avstring.h"
+#include "avformat.h"
+#include "internal.h"
+#include <unistd.h>
+
+/*
+ * An apple http stream consists of a playlist with media segment files,
+ * played sequentially. There may be several playlists with the same
+ * video content, in different bandwidth variants, that are played in
+ * parallel (preferrably only one bandwidth variant at a time). In this case,
+ * the user supplied the url to a main playlist that only lists the variant
+ * playlists.
+ *
+ * If the main playlist doesn't point at any variants, we still create
+ * one anonymous toplevel variant for this, to maintain the structure.
+ */
+
+struct segment {
+    int duration;
+    char url[MAX_URL_SIZE];
+};
+
+struct variant {
+    int bandwidth;
+    char url[MAX_URL_SIZE];
+};
+
+typedef struct AppleHTTPContext {
+    char playlisturl[MAX_URL_SIZE];
+    int target_duration;
+    int start_seq_no;
+    int finished;
+    int n_segments;
+    struct segment **segments;
+    int n_variants;
+    struct variant **variants;
+    int cur_seq_no;
+    URLContext *seg_hd;
+    int64_t last_load_time;
+} AppleHTTPContext;
+
+static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
+{
+    int len = ff_get_line(s, buf, maxlen);
+    while (len > 0 && isspace(buf[len - 1]))
+        buf[--len] = '\0';
+    return len;
+}
+
+static void make_absolute_url(char *buf, int size, const char *base,
+                              const char *rel)
+{
+    char *sep;
+    /* Absolute path, relative to the current server */
+    if (base && strstr(base, "://") && rel[0] == '/') {
+        if (base != buf)
+            av_strlcpy(buf, base, size);
+        sep = strstr(buf, "://");
+        if (sep) {
+            sep += 3;
+            sep = strchr(sep, '/');
+            if (sep)
+                *sep = '\0';
+        }
+        av_strlcat(buf, rel, size);
+        return;
+    }
+    /* If rel actually is an absolute url, just copy it */
+    if (!base || strstr(rel, "://") || rel[0] == '/') {
+        av_strlcpy(buf, rel, size);
+        return;
+    }
+    if (base != buf)
+        av_strlcpy(buf, base, size);
+    /* Remove the file name from the base url */
+    sep = strrchr(buf, '/');
+    if (sep)
+        sep[1] = '\0';
+    else
+        buf[0] = '\0';
+    while (av_strstart(rel, "../", NULL) && sep) {
+        /* Remove the path delimiter at the end */
+        sep[0] = '\0';
+        sep = strrchr(buf, '/');
+        /* If the next directory name to pop off is "..", break here */
+        if (!strcmp(sep ? &sep[1] : buf, "..")) {
+            /* Readd the slash we just removed */
+            av_strlcat(buf, "/", size);
+            break;
+        }
+        /* Cut off the directory name */
+        if (sep)
+            sep[1] = '\0';
+        else
+            buf[0] = '\0';
+        rel += 3;
+    }
+    av_strlcat(buf, rel, size);
+}
+
+static void free_segment_list(AppleHTTPContext *s)
+{
+    int i;
+    for (i = 0; i < s->n_segments; i++)
+        av_free(s->segments[i]);
+    av_freep(&s->segments);
+    s->n_segments = 0;
+}
+
+static void free_variant_list(AppleHTTPContext *s)
+{
+    int i;
+    for (i = 0; i < s->n_variants; i++)
+        av_free(s->variants[i]);
+    av_freep(&s->variants);
+    s->n_variants = 0;
+}
+
+struct variant_info {
+    char bandwidth[20];
+};
+
+static void handle_variant_args(struct variant_info *info, const char *key,
+                                int key_len, char **dest, int *dest_len)
+{
+    if (!strncmp(key, "BANDWIDTH=", key_len)) {
+        *dest     =        info->bandwidth;
+        *dest_len = sizeof(info->bandwidth);
+    }
+}
+
+static int parse_playlist(URLContext *h, const char *url)
+{
+    AppleHTTPContext *s = h->priv_data;
+    AVIOContext *in;
+    int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
+    char line[1024];
+    const char *ptr;
+
+    if ((ret = avio_open(&in, url, URL_RDONLY)) < 0)
+        return ret;
+
+    read_chomp_line(in, line, sizeof(line));
+    if (strcmp(line, "#EXTM3U"))
+        return AVERROR_INVALIDDATA;
+
+    free_segment_list(s);
+    s->finished = 0;
+    while (!url_feof(in)) {
+        read_chomp_line(in, line, sizeof(line));
+        if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
+            struct variant_info info = {{0}};
+            is_variant = 1;
+            ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
+                               &info);
+            bandwidth = atoi(info.bandwidth);
+        } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
+            s->target_duration = atoi(ptr);
+        } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
+            s->start_seq_no = atoi(ptr);
+        } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
+            s->finished = 1;
+        } else if (av_strstart(line, "#EXTINF:", &ptr)) {
+            is_segment = 1;
+            duration = atoi(ptr);
+        } else if (av_strstart(line, "#", NULL)) {
+            continue;
+        } else if (line[0]) {
+            if (is_segment) {
+                struct segment *seg = av_malloc(sizeof(struct segment));
+                if (!seg) {
+                    ret = AVERROR(ENOMEM);
+                    goto fail;
+                }
+                seg->duration = duration;
+                make_absolute_url(seg->url, sizeof(seg->url), url, line);
+                dynarray_add(&s->segments, &s->n_segments, seg);
+                is_segment = 0;
+            } else if (is_variant) {
+                struct variant *var = av_malloc(sizeof(struct variant));
+                if (!var) {
+                    ret = AVERROR(ENOMEM);
+                    goto fail;
+                }
+                var->bandwidth = bandwidth;
+                make_absolute_url(var->url, sizeof(var->url), url, line);
+                dynarray_add(&s->variants, &s->n_variants, var);
+                is_variant = 0;
+            }
+        }
+    }
+    s->last_load_time = av_gettime();
+
+fail:
+    avio_close(in);
+    return ret;
+}
+
+static int applehttp_open(URLContext *h, const char *uri, int flags)
+{
+    AppleHTTPContext *s;
+    int ret, i;
+    const char *nested_url;
+
+    if (flags & (URL_WRONLY | URL_RDWR))
+        return AVERROR_NOTSUPP;
+
+    s = av_mallocz(sizeof(AppleHTTPContext));
+    if (!s)
+        return AVERROR(ENOMEM);
+    h->priv_data = s;
+    h->is_streamed = 1;
+
+    if (av_strstart(uri, "applehttp+", &nested_url)) {
+        av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
+    } else if (av_strstart(uri, "applehttp://", &nested_url)) {
+        av_strlcpy(s->playlisturl, "http://", sizeof(s->playlisturl));
+        av_strlcat(s->playlisturl, nested_url, sizeof(s->playlisturl));
+    } else {
+        av_log(NULL, AV_LOG_ERROR, "Unsupported url %s\n", uri);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    if ((ret = parse_playlist(h, s->playlisturl)) < 0)
+        goto fail;
+
+    if (s->n_segments == 0 && s->n_variants > 0) {
+        int max_bandwidth = 0, maxvar = -1;
+        for (i = 0; i < s->n_variants; i++) {
+            if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
+                max_bandwidth = s->variants[i]->bandwidth;
+                maxvar = i;
+            }
+        }
+        av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
+                   sizeof(s->playlisturl));
+        if ((ret = parse_playlist(h, s->playlisturl)) < 0)
+            goto fail;
+    }
+
+    if (s->n_segments == 0) {
+        av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
+        ret = AVERROR(EIO);
+        goto fail;
+    }
+    s->cur_seq_no = s->start_seq_no;
+    if (!s->finished && s->n_segments >= 3)
+        s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
+
+    return 0;
+
+fail:
+    av_free(s);
+    return ret;
+}
+
+static int applehttp_read(URLContext *h, uint8_t *buf, int size)
+{
+    AppleHTTPContext *s = h->priv_data;
+    const char *url;
+    int ret;
+
+start:
+    if (s->seg_hd) {
+        ret = url_read(s->seg_hd, buf, size);
+        if (ret > 0)
+            return ret;
+    }
+    if (s->seg_hd) {
+        url_close(s->seg_hd);
+        s->seg_hd = NULL;
+        s->cur_seq_no++;
+    }
+retry:
+    if (!s->finished) {
+        int64_t now = av_gettime();
+        if (now - s->last_load_time >= s->target_duration*1000000)
+            if ((ret = parse_playlist(h, s->playlisturl)) < 0)
+                return ret;
+    }
+    if (s->cur_seq_no < s->start_seq_no) {
+        av_log(NULL, AV_LOG_WARNING,
+               "skipping %d segments ahead, expired from playlist\n",
+               s->start_seq_no - s->cur_seq_no);
+        s->cur_seq_no = s->start_seq_no;
+    }
+    if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
+        if (s->finished)
+            return AVERROR_EOF;
+        while (av_gettime() - s->last_load_time < s->target_duration*1000000) {
+            if (url_interrupt_cb())
+                return AVERROR(EINTR);
+            usleep(100*1000);
+        }
+        goto retry;
+    }
+    url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
+    av_log(NULL, AV_LOG_DEBUG, "opening %s\n", url);
+    ret = url_open(&s->seg_hd, url, URL_RDONLY);
+    if (ret < 0) {
+        if (url_interrupt_cb())
+            return AVERROR(EINTR);
+        av_log(NULL, AV_LOG_WARNING, "Unable to open %s\n", url);
+        s->cur_seq_no++;
+        goto retry;
+    }
+    goto start;
+}
+
+static int applehttp_close(URLContext *h)
+{
+    AppleHTTPContext *s = h->priv_data;
+
+    free_segment_list(s);
+    free_variant_list(s);
+    url_close(s->seg_hd);
+    av_free(s);
+    return 0;
+}
+
+URLProtocol ff_applehttp_protocol = {
+    "applehttp",
+    applehttp_open,
+    applehttp_read,
+    NULL, /* write */
+    NULL, /* seek */
+    applehttp_close,
+    .flags = URL_PROTOCOL_FLAG_NESTED_SCHEME,
+};