dashenc: Don't require the stream bitrate to be known

Don't write any bitrate attribute if it isn't known. As long as one
doesn't want automatic bitrate switching, playback can work just
fine even if it isn't set.

If strict standard compliance is requested, this is still considered
an error, since the attribute is mandatory according to the spec.

Based on a patch by Rodger Combs.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/dashenc.c

@@ -59,6 +59,7 @@ typedef struct OutputStream {
     int nb_segments, segments_size, segment_index;
     Segment **segments;
     int64_t first_dts, start_dts, end_dts;
+    char bandwidth_str[64];
 
     char codec_str[100];
 } OutputStream;
@@ -368,7 +369,7 @@ static int write_manifest(AVFormatContext *s, int final)
             OutputStream *os = &c->streams[i];
             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
                 continue;
-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\" bandwidth=\"%d\" width=\"%d\" height=\"%d\">\n", i, os->codec_str, st->codec->bit_rate, st->codec->width, st->codec->height);
+            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, st->codec->width, st->codec->height);
             output_segment_list(&c->streams[i], out, c);
             avio_printf(out, "\t\t\t</Representation>\n");
         }
@@ -381,7 +382,7 @@ static int write_manifest(AVFormatContext *s, int final)
             OutputStream *os = &c->streams[i];
             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                 continue;
-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\" bandwidth=\"%d\" audioSamplingRate=\"%d\">\n", i, os->codec_str, st->codec->bit_rate, st->codec->sample_rate);
+            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, st->codec->sample_rate);
             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
             output_segment_list(&c->streams[i], out, c);
             avio_printf(out, "\t\t\t</Representation>\n");
@@ -439,10 +440,17 @@ static int dash_write_header(AVFormatContext *s)
         AVDictionary *opts = NULL;
         char filename[1024];
 
-        if (!s->streams[i]->codec->bit_rate) {
-            av_log(s, AV_LOG_ERROR, "No bit rate set for stream %d\n", i);
-            ret = AVERROR(EINVAL);
-            goto fail;
+        if (s->streams[i]->codec->bit_rate) {
+            snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
+                     " bandwidth=\"%d\"", s->streams[i]->codec->bit_rate);
+        } else {
+            int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
+                        AV_LOG_ERROR : AV_LOG_WARNING;
+            av_log(s, level, "No bit rate set for stream %d\n", i);
+            if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
         }
 
         ctx = avformat_alloc_context();