On Fri, 27 Jan 2017, Peter Große wrote:
This patch is based on the stream assignment code in webmdashenc.
This muxer isn't available in libav, so the reference doesn't really work
in context here.
Additional changes:
* Default to one AdaptationSet per stream
Previously all mapped streams of a media type (video, audio) where assigned
to a single AdaptationSet. Using the DASH live profile it is mandatory, that
the segments of all representations are aligned, which is currently not
enforced. This leads to problems when using video streams with different
key frame intervals. So to play safe, default to one AdaptationSet per
stream,
unless overwritten by explicit assignment
Is there any way to easily get it back to the original behaviour, e.g.
tell it to group all audio tracks together and all video tracks together,
without having to manually specify the stream numbers?
* Make sure all streams are assigned to exactly one AdaptationSet
Signed-off-by: Peter Große <[email protected]>
---
libavformat/dashenc.c | 193 ++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 162 insertions(+), 31 deletions(-)
diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 1b12d4f..c561ad1 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -24,6 +24,7 @@
#include <unistd.h>
#endif
+#include "libavutil/avutil.h"
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/intreadwrite.h"
@@ -58,9 +59,15 @@ typedef struct Segment {
int n;
} Segment;
+typedef struct AdaptationSet {
+ char id[10];
+ enum AVMediaType media_type;
+ AVDictionary *metadata;
+} AdaptationSet;
+
typedef struct OutputStream {
AVFormatContext *ctx;
- int ctx_inited;
+ int ctx_inited, as_idx;
uint8_t iobuf[32768];
AVIOContext *out;
int duration_written;
@@ -79,6 +86,9 @@ typedef struct OutputStream {
typedef struct DASHContext {
const AVClass *class; /* Class for private options. */
+ char *adaptation_sets;
+ AdaptationSet *as;
+ int nb_as;
int window_size;
int extra_window_size;
int min_seg_duration;
@@ -87,7 +97,7 @@ typedef struct DASHContext {
int use_timeline;
int single_file;
OutputStream *streams;
- int has_video, has_audio;
+ int has_video;
int64_t last_duration;
int64_t total_duration;
char availability_start_time[100];
@@ -176,6 +186,16 @@ static void dash_free(AVFormatContext *s)
{
DASHContext *c = s->priv_data;
int i, j;
+
+ if (c->as) {
+ for (i = 0; i < c->nb_as; i++) {
+ if (&c->as[i].metadata)
+ av_dict_free(&c->as[i].metadata);
+ }
+ av_freep(&c->as);
+ c->nb_as = 0;
+ }
+
if (!c->streams)
return;
for (i = 0; i < s->nb_streams; i++) {
@@ -436,12 +456,144 @@ static void format_date_now(char *buf, int size)
}
}
+static int write_adaptation_set(AVFormatContext *s, AVIOContext *out, int
as_index)
+{
+ DASHContext *c = s->priv_data;
+ AdaptationSet *as = &c->as[as_index];
+ int i;
+
+ avio_printf(out, "\t\t<AdaptationSet id=\"%s\" contentType=\"%s\" segmentAlignment=\"true\"
bitstreamSwitching=\"true\">\n",
+ as->id, as->media_type == AVMEDIA_TYPE_VIDEO ? "video" :
"audio");
+
+ for (i = 0; i < s->nb_streams; i++) {
+ OutputStream *os = &c->streams[i];
+
+ if (os->as_idx - 1 != as_index)
+ continue;
+
+ if (as->media_type == AVMEDIA_TYPE_VIDEO) {
+ avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s
width=\"%d\" height=\"%d\">\n",
+ i, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->width,
s->streams[i]->codecpar->height);
+ } else {
+ avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\"
codecs=\"%s\"%s audioSamplingRate=\"%d\">\n",
+ i, os->codec_str, os->bandwidth_str,
s->streams[i]->codecpar->sample_rate);
+ avio_printf(out, "\t\t\t\t<AudioChannelConfiguration
schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\"
/>\n",
+ s->streams[i]->codecpar->channels);
+ }
+ output_segment_list(os, out, c);
+ avio_printf(out, "\t\t\t</Representation>\n");
+ }
+ avio_printf(out, "\t\t</AdaptationSet>\n");
+
+ return 0;
+}
+
+static int parse_adaptation_sets(AVFormatContext *s)
+{
+ DASHContext *c = s->priv_data;
+ char *p = c->adaptation_sets;
+ char *q;
+ enum { new_set, parse_id, parsing_streams } state;
+ int i;
+
+ /* default: one AdaptationSet for each stream */
+ if (!p) {
+ void *mem = av_mallocz(sizeof(*c->as) * s->nb_streams);
+ if (!mem)
+ return AVERROR(ENOMEM);
+ c->as = mem;
+ c->nb_as = s->nb_streams;
+
+ for (i = 0; i < s->nb_streams; i++) {
+ AdaptationSet *as = &c->as[i];
+ OutputStream *os = &c->streams[i];
+ snprintf(as->id, sizeof(as->id), "%d", i);
+ as->metadata = NULL;
+ as->media_type = s->streams[i]->codecpar->codec_type;
+ os->as_idx = i + 1;
+ }
+ return 0;
+ }
+
+ /* syntax id=0,streams=0,1,2 id=1,streams=3,4 and so on */
+ state = new_set;
+ while (p < c->adaptation_sets + strlen(c->adaptation_sets)) {
Isn't this equivalent to "while (*p) {"?
+ if (*p == ' ') {
+ continue;
If this ever happens, wouldn't you end up in an infinite loop?
+ } else if (state == new_set && !strncmp(p, "id=", 3)) {
Instead of strncmp, you can also use av_strstart to avoid having to
hardcode the number of chars.
+ AdaptationSet *as;
+ void *mem = av_realloc(c->as, sizeof(*c->as) * (c->nb_as + 1));
+ if (!mem)
+ return AVERROR(ENOMEM);
+ c->as = mem;
+ ++c->nb_as;
+
+ as = &c->as[c->nb_as - 1];
+ as->metadata = NULL;
maybe memset(as, 0, sizeof(*as))? Then you'd reduce the risk of missing to
initialize a new field here, if AdaptationSet is expanded later.
+ as->media_type = AVMEDIA_TYPE_UNKNOWN;
+
+ p += 3; // consume "id="
av_strstart can avoid hardcoding this number here
+ q = as->id;
+ while (*p != ',') *q++ = *p++;
Keep normal indentation for the assignment.
The loop lacks a condition for *p == '\0', so unless there's a trailing
comma somewhere, you'll run out of bounds and crash.
It also lacks a check for the buffer size of as->id.
Something like this could also work:
n = strcspn(p, ",");
snprintf(as->id, sizeof(as->id), "%*s", n, p);
p += n;
if (*p)
p++;
+ *q = 0;
+ p++;
+ state = parse_id;
+ } else if (state == parse_id && !strncmp(p, "streams=", 8)) {
+ p += 8; // consume "streams="
+ state = parsing_streams;
+ } else if (state == parsing_streams) {
+ struct AdaptationSet *as = &c->as[c->nb_as - 1];
+ OutputStream *os;
+ char *stream_identifier;
+
+ q = p;
+ while (*q != '\0' && *q != ',' && *q != ' ') q++;
+ stream_identifier = av_strndup(p, q - p);
This should also be doable with strcspn(p, " ,"). And copy it into a local
stack buffer (e.g. with snprintf as above, to get bounds checking of that
buffer for free) instead of a strdup of a couple-bytes string.
+
+ i = strtol(stream_identifier, NULL, 10);
+ if (i < 0 || i >= s->nb_streams) {
+ av_log(s, AV_LOG_ERROR, "Selected stream \"%s\" not found!\n",
stream_identifier);
If you hit this case, you leak stream_identifier (unless you make it a
local stack buffer as I suggested).
+ return -1;
Please return proper error codes, e.g. AVERROR(EINVAL) here.
// Martin
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