Add Apple HTTP Live Streaming demuxer

Originally committed as revision 24834 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 578 insertions, 0 deletions

diff --git a/libavformat/applehttp.c b/libavformat/applehttp.c
new file mode 100644
index 0000000000..3d8b61d70c
--- /dev/null
+++ b/libavformat/applehttp.c
@@ -0,0 +1,578 @@
+/*
+ * Apple HTTP Live Streaming demuxer
+ * 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 demuxer
+ * http://tools.ietf.org/html/draft-pantos-http-live-streaming
+ */
+
+#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];
+};
+
+/*
+ * Each variant has its own demuxer. If it currently is active,
+ * it has an open ByteIOContext too, and potentially an AVPacket
+ * containing the next packet from this stream.
+ */
+struct variant {
+    int bandwidth;
+    char url[MAX_URL_SIZE];
+    ByteIOContext *pb;
+    AVFormatContext *ctx;
+    AVPacket pkt;
+    int stream_offset;
+
+    int start_seq_no;
+    int n_segments;
+    struct segment **segments;
+    int needed;
+};
+
+typedef struct AppleHTTPContext {
+    int target_duration;
+    int finished;
+    int n_variants;
+    struct variant **variants;
+    int cur_seq_no;
+    int64_t last_load_time;
+    int64_t last_packet_dts;
+    int max_start_seq, min_end_seq;
+} AppleHTTPContext;
+
+static int read_chomp_line(ByteIOContext *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;
+    if (!base || strstr(rel, "://")) {
+        av_strlcpy(buf, rel, size);
+        return;
+    }
+    if (base != buf)
+        av_strlcpy(buf, base, size);
+    sep = strrchr(buf, '/');
+    if (sep)
+        sep[1] = '\0';
+    while (av_strstart(rel, "../", NULL)) {
+        if (sep) {
+            sep[0] = '\0';
+            sep = strrchr(buf, '/');
+            if (sep)
+                sep[1] = '\0';
+        }
+        rel += 3;
+    }
+    av_strlcat(buf, rel, size);
+}
+
+static void free_segment_list(struct variant *var)
+{
+    int i;
+    for (i = 0; i < var->n_segments; i++)
+        av_free(var->segments[i]);
+    av_freep(&var->segments);
+    var->n_segments = 0;
+}
+
+static void free_variant_list(AppleHTTPContext *c)
+{
+    int i;
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *var = c->variants[i];
+        free_segment_list(var);
+        av_free_packet(&var->pkt);
+        if (var->pb)
+            url_fclose(var->pb);
+        if (var->ctx) {
+            var->ctx->pb = NULL;
+            av_close_input_file(var->ctx);
+        }
+        av_free(var);
+    }
+    av_freep(&c->variants);
+    c->n_variants = 0;
+}
+
+/*
+ * Used to reset a statically allocated AVPacket to a clean slate,
+ * containing no data.
+ */
+static void reset_packet(AVPacket *pkt)
+{
+    av_init_packet(pkt);
+    pkt->data = NULL;
+}
+
+static struct variant *new_variant(AppleHTTPContext *c, int bandwidth,
+                                   const char *url, const char *base)
+{
+    struct variant *var = av_mallocz(sizeof(struct variant));
+    if (!var)
+        return NULL;
+    reset_packet(&var->pkt);
+    var->bandwidth = bandwidth;
+    make_absolute_url(var->url, sizeof(var->url), base, url);
+    dynarray_add(&c->variants, &c->n_variants, var);
+    return var;
+}
+
+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(AppleHTTPContext *c, const char *url,
+                          struct variant *var, ByteIOContext *in)
+{
+    int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
+    char line[1024];
+    const char *ptr;
+    int close_in = 0;
+
+    if (!in) {
+        close_in = 1;
+        if ((ret = url_fopen(&in, url, URL_RDONLY)) < 0)
+            return ret;
+    }
+
+    read_chomp_line(in, line, sizeof(line));
+    if (strcmp(line, "#EXTM3U")) {
+        ret = AVERROR_INVALIDDATA;
+        goto fail;
+    }
+
+    if (var)
+        free_segment_list(var);
+    c->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)) {
+            c->target_duration = atoi(ptr);
+        } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
+            if (!var) {
+                var = new_variant(c, 0, url, NULL);
+                if (!var) {
+                    ret = AVERROR(ENOMEM);
+                    goto fail;
+                }
+            }
+            var->start_seq_no = atoi(ptr);
+        } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
+            c->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_variant) {
+                if (!new_variant(c, bandwidth, line, url)) {
+                    ret = AVERROR(ENOMEM);
+                    goto fail;
+                }
+                is_variant = 0;
+                bandwidth  = 0;
+            }
+            if (is_segment) {
+                struct segment *seg;
+                if (!var) {
+                    var = new_variant(c, 0, url, NULL);
+                    if (!var) {
+                        ret = AVERROR(ENOMEM);
+                        goto fail;
+                    }
+                }
+                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(&var->segments, &var->n_segments, seg);
+                is_segment = 0;
+            }
+        }
+    }
+    c->last_load_time = av_gettime();
+
+fail:
+    if (close_in)
+        url_fclose(in);
+    return ret;
+}
+
+static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+    AppleHTTPContext *c = s->priv_data;
+    int ret = 0, i, j, stream_offset = 0;
+
+    if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
+        goto fail;
+
+    if (c->n_variants == 0) {
+        av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
+        ret = AVERROR_EOF;
+        goto fail;
+    }
+    /* If the playlist only contained variants, parse each individual
+     * variant playlist. */
+    if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
+        for (i = 0; i < c->n_variants; i++) {
+            struct variant *v = c->variants[i];
+            if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
+                goto fail;
+        }
+    }
+
+    if (c->variants[0]->n_segments == 0) {
+        av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
+        ret = AVERROR_EOF;
+        goto fail;
+    }
+
+    /* If this isn't a live stream, calculate the total duration of the
+     * stream. */
+    if (c->finished) {
+        int duration = 0;
+        for (i = 0; i < c->variants[0]->n_segments; i++)
+            duration += c->variants[0]->segments[i]->duration;
+        s->duration = duration * AV_TIME_BASE;
+    }
+
+    c->min_end_seq = INT_MAX;
+    /* Open the demuxer for each variant */
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *v = c->variants[i];
+        if (v->n_segments == 0)
+            continue;
+        c->max_start_seq = FFMAX(c->max_start_seq, v->start_seq_no);
+        c->min_end_seq   = FFMIN(c->min_end_seq,   v->start_seq_no +
+                                                   v->n_segments);
+        ret = av_open_input_file(&v->ctx, v->segments[0]->url, NULL, 0, NULL);
+        if (ret < 0)
+            goto fail;
+        url_fclose(v->ctx->pb);
+        v->ctx->pb = NULL;
+        v->stream_offset = stream_offset;
+        /* Create new AVStreams for each stream in this variant */
+        for (j = 0; j < v->ctx->nb_streams; j++) {
+            AVStream *st = av_new_stream(s, i);
+            if (!st) {
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
+            avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
+        }
+        stream_offset += v->ctx->nb_streams;
+    }
+    c->last_packet_dts = AV_NOPTS_VALUE;
+
+    c->cur_seq_no = c->max_start_seq;
+    /* If this is a live stream with more than 3 segments, start at the
+     * third last segment. */
+    if (!c->finished && c->min_end_seq - c->max_start_seq > 3)
+        c->cur_seq_no = c->min_end_seq - 2;
+
+    return 0;
+fail:
+    free_variant_list(c);
+    return ret;
+}
+
+static int open_variant(AppleHTTPContext *c, struct variant *var, int skip)
+{
+    int ret;
+
+    if (c->cur_seq_no < var->start_seq_no) {
+        av_log(NULL, AV_LOG_WARNING,
+               "seq %d not available in variant %s, skipping\n",
+               var->start_seq_no, var->url);
+        return 0;
+    }
+    if (c->cur_seq_no - var->start_seq_no >= var->n_segments)
+        return c->finished ? AVERROR_EOF : 0;
+    ret = url_fopen(&var->pb,
+                    var->segments[c->cur_seq_no - var->start_seq_no]->url,
+                    URL_RDONLY);
+    if (ret < 0)
+        return ret;
+    var->ctx->pb = var->pb;
+    /* If this is a new segment in parallel with another one already opened,
+     * skip ahead so they're all at the same dts. */
+    if (skip && c->last_packet_dts != AV_NOPTS_VALUE) {
+        while (1) {
+            ret = av_read_frame(var->ctx, &var->pkt);
+            if (ret < 0) {
+                if (ret == AVERROR_EOF) {
+                    reset_packet(&var->pkt);
+                    return 0;
+                }
+                return ret;
+            }
+            if (var->pkt.dts >= c->last_packet_dts)
+                break;
+            av_free_packet(&var->pkt);
+        }
+    }
+    return 0;
+}
+
+static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    AppleHTTPContext *c = s->priv_data;
+    int ret, i, minvariant = -1, first = 1, needed = 0, changed = 0,
+        variants = 0;
+
+    /* Recheck the discard flags - which streams are desired at the moment */
+    for (i = 0; i < c->n_variants; i++)
+        c->variants[i]->needed = 0;
+    for (i = 0; i < s->nb_streams; i++) {
+        AVStream *st = s->streams[i];
+        struct variant *var = c->variants[s->streams[i]->id];
+        if (st->discard < AVDISCARD_ALL) {
+            var->needed = 1;
+            needed++;
+        }
+        /* Copy the discard flag to the chained demuxer, to indicate which
+         * streams are desired. */
+        var->ctx->streams[i - var->stream_offset]->discard = st->discard;
+    }
+    if (!needed)
+        return AVERROR_EOF;
+start:
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *var = c->variants[i];
+        /* Close unneeded streams, open newly requested streams */
+        if (var->pb && !var->needed) {
+            av_log(s, AV_LOG_DEBUG,
+                   "Closing variant stream %d, no longer needed\n", i);
+            av_free_packet(&var->pkt);
+            reset_packet(&var->pkt);
+            url_fclose(var->pb);
+            var->pb = NULL;
+            changed = 1;
+        } else if (!var->pb && var->needed) {
+            if (first)
+                av_log(s, AV_LOG_DEBUG, "Opening variant stream %d\n", i);
+            if (first && !c->finished)
+                if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
+                    return ret;
+            ret = open_variant(c, var, first);
+            if (ret < 0)
+                return ret;
+            changed = 1;
+        }
+        /* Count the number of open variants */
+        if (var->pb)
+            variants++;
+        /* Make sure we've got one buffered packet from each open variant
+         * stream */
+        if (var->pb && !var->pkt.data) {
+            ret = av_read_frame(var->ctx, &var->pkt);
+            if (ret < 0) {
+                if (!url_feof(var->pb))
+                    return ret;
+                reset_packet(&var->pkt);
+            }
+        }
+        /* Check if this stream has the packet with the lowest dts */
+        if (var->pkt.data) {
+            if (minvariant < 0 ||
+                var->pkt.dts < c->variants[minvariant]->pkt.dts)
+                minvariant = i;
+        }
+    }
+    if (first && changed)
+        av_log(s, AV_LOG_INFO, "Receiving %d variant streams\n", variants);
+    /* If we got a packet, return it */
+    if (minvariant >= 0) {
+        *pkt = c->variants[minvariant]->pkt;
+        pkt->stream_index += c->variants[minvariant]->stream_offset;
+        reset_packet(&c->variants[minvariant]->pkt);
+        c->last_packet_dts = pkt->dts;
+        return 0;
+    }
+    /* No more packets - eof reached in all variant streams, close the
+     * current segments. */
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *var = c->variants[i];
+        if (var->pb) {
+            url_fclose(var->pb);
+            var->pb = NULL;
+        }
+    }
+    /* Indicate that we're opening the next segment, not opening a new
+     * variant stream in parallel, so we shouldn't try to skip ahead. */
+    first = 0;
+    c->cur_seq_no++;
+reload:
+    if (!c->finished) {
+        /* If this is a live stream and target_duration has elapsed since
+         * the last playlist reload, reload the variant playlists now. */
+        int64_t now = av_gettime();
+        if (now - c->last_load_time >= c->target_duration*1000000) {
+            c->max_start_seq = 0;
+            c->min_end_seq   = INT_MAX;
+            for (i = 0; i < c->n_variants; i++) {
+                struct variant *var = c->variants[i];
+                if (var->needed) {
+                    if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
+                        return ret;
+                    c->max_start_seq = FFMAX(c->max_start_seq,
+                                             var->start_seq_no);
+                    c->min_end_seq   = FFMIN(c->min_end_seq,
+                                             var->start_seq_no + var->n_segments);
+                }
+            }
+        }
+    }
+    if (c->cur_seq_no < c->max_start_seq) {
+        av_log(NULL, AV_LOG_WARNING,
+               "skipping %d segments ahead, expired from playlists\n",
+               c->max_start_seq - c->cur_seq_no);
+        c->cur_seq_no = c->max_start_seq;
+    }
+    /* If more segments exit, open the next one */
+    if (c->cur_seq_no < c->min_end_seq)
+        goto start;
+    /* We've reached the end of the playlists - return eof if this is a
+     * non-live stream, wait until the next playlist reload if it is live. */
+    if (c->finished)
+        return AVERROR_EOF;
+    while (av_gettime() - c->last_load_time < c->target_duration*1000000) {
+        if (url_interrupt_cb())
+            return AVERROR(EINTR);
+        usleep(100*1000);
+    }
+    /* Enough time has elapsed since the last reload */
+    goto reload;
+}
+
+static int applehttp_close(AVFormatContext *s)
+{
+    AppleHTTPContext *c = s->priv_data;
+
+    free_variant_list(c);
+    return 0;
+}
+
+static int applehttp_read_seek(AVFormatContext *s, int stream_index,
+                               int64_t timestamp, int flags)
+{
+    AppleHTTPContext *c = s->priv_data;
+    int pos = 0, i;
+    struct variant *var = c->variants[0];
+
+    if ((flags & AVSEEK_FLAG_BYTE) || !c->finished)
+        return AVERROR(ENOSYS);
+
+    /* Reset the variants */
+    c->last_packet_dts = AV_NOPTS_VALUE;
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *var = c->variants[i];
+        if (var->pb) {
+            url_fclose(var->pb);
+            var->pb = NULL;
+        }
+        av_free_packet(&var->pkt);
+        reset_packet(&var->pkt);
+    }
+
+    timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
+                               s->streams[stream_index]->time_base.den :
+                               AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
+                               AV_ROUND_DOWN : AV_ROUND_UP);
+    /* Locate the segment that contains the target timestamp */
+    for (i = 0; i < var->n_segments; i++) {
+        if (timestamp >= pos && timestamp < pos + var->segments[i]->duration) {
+            c->cur_seq_no = var->start_seq_no + i;
+            return 0;
+        }
+        pos += var->segments[i]->duration;
+    }
+    return AVERROR(EIO);
+}
+
+static int applehttp_probe(AVProbeData *p)
+{
+    /* Require #EXTM3U at the start, and either one of the ones below
+     * somewhere for a proper match. */
+    if (strncmp(p->buf, "#EXTM3U", 7))
+        return 0;
+    if (strstr(p->buf, "#EXT-X-STREAM-INF:")     ||
+        strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
+        strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
+        return AVPROBE_SCORE_MAX;
+    return 0;
+}
+
+AVInputFormat applehttp_demuxer = {
+    "applehttp",
+    NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
+    sizeof(AppleHTTPContext),
+    applehttp_probe,
+    applehttp_read_header,
+    applehttp_read_packet,
+    applehttp_close,
+    applehttp_read_seek,
+};