avformat/tee: Handling slave failure in tee muxer

Adds per slave option 'onfail' to the tee muxer allowing an output to
fail, so other slave outputs can continue.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Jan Sebechlebsky <sebechlebskyjan@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

doc/muxers.texi

@@ -1453,6 +1453,12 @@ Select the streams that should be mapped to the slave output,
 specified by a stream specifier. If not specified, this defaults to
 all the input streams. You may use multiple stream specifiers
 separated by commas (@code{,}) e.g.: @code{a:0,v}
+
+@item onfail
+Specify behaviour on output failure. This can be set to either @code{abort} (which is
+default) or @code{ignore}. @code{abort} will cause whole process to fail in case of failure
+on this slave output. @code{ignore} will ignore failure on this output, so other outputs
+will continue without being affected.
 @end table
 
 @subsection Examples
@@ -1466,6 +1472,14 @@ ffmpeg -i ... -c:v libx264 -c:a mp2 -f tee -map 0:v -map 0:a
   "archive-20121107.mkv|[f=mpegts]udp://10.0.1.255:1234/"
 @end example
 
+@item
+As above, but continue streaming even if output to local file fails
+(for example local drive fills up):
+@example
+ffmpeg -i ... -c:v libx264 -c:a mp2 -f tee -map 0:v -map 0:a
+  "[onfail=ignore]archive-20121107.mkv|[f=mpegts]udp://10.0.1.255:1234/"
+@end example
+
 @item
 Use @command{ffmpeg} to encode the input, and send the output
 to three different destinations. The @code{dump_extra} bitstream

libavformat/tee.c

@@ -29,10 +29,19 @@
 
 #define MAX_SLAVES 16
 
+typedef enum {
+    ON_SLAVE_FAILURE_ABORT  = 1,
+    ON_SLAVE_FAILURE_IGNORE = 2
+} SlaveFailurePolicy;
+
+#define DEFAULT_SLAVE_FAILURE_POLICY ON_SLAVE_FAILURE_ABORT
+
 typedef struct {
     AVFormatContext *avf;
     AVBitStreamFilterContext **bsfs; ///< bitstream filters per stream
 
+    SlaveFailurePolicy on_fail;
+
     /** map from input to output streams indexes,
      * disabled output streams are set to -1 */
     int *stream_map;
@@ -42,6 +51,7 @@ typedef struct {
 typedef struct TeeContext {
     const AVClass *class;
     unsigned nb_slaves;
+    unsigned nb_alive;
     TeeSlave slaves[MAX_SLAVES];
 } TeeContext;
 
@@ -136,6 +146,23 @@ end:
     return ret;
 }
 
+static inline int parse_slave_failure_policy_option(const char *opt, TeeSlave *tee_slave)
+{
+    if (!opt) {
+        tee_slave->on_fail = DEFAULT_SLAVE_FAILURE_POLICY;
+        return 0;
+    } else if (!av_strcasecmp("abort", opt)) {
+        tee_slave->on_fail = ON_SLAVE_FAILURE_ABORT;
+        return 0;
+    } else if (!av_strcasecmp("ignore", opt)) {
+        tee_slave->on_fail = ON_SLAVE_FAILURE_IGNORE;
+        return 0;
+    }
+    /* Set failure behaviour to abort, so invalid option error will not be ignored */
+    tee_slave->on_fail = ON_SLAVE_FAILURE_ABORT;
+    return AVERROR(EINVAL);
+}
+
 static int close_slave(TeeSlave *tee_slave)
 {
     AVFormatContext *avf;
@@ -184,7 +211,7 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
     AVDictionary *options = NULL;
     AVDictionaryEntry *entry;
     char *filename;
-    char *format = NULL, *select = NULL;
+    char *format = NULL, *select = NULL, *on_fail = NULL;
     AVFormatContext *avf2 = NULL;
     AVStream *st, *st2;
     int stream_count;
@@ -204,6 +231,14 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
 
     STEAL_OPTION("f", format);
     STEAL_OPTION("select", select);
+    STEAL_OPTION("onfail", on_fail);
+
+    ret = parse_slave_failure_policy_option(on_fail, tee_slave);
+    if (ret < 0) {
+        av_log(avf, AV_LOG_ERROR,
+               "Invalid onfail option value, valid options are 'abort' and 'ignore'\n");
+        goto end;
+    }
 
     ret = avformat_alloc_output_context2(&avf2, NULL, format, filename);
     if (ret < 0)
@@ -351,6 +386,7 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
 end:
     av_free(format);
     av_free(select);
+    av_free(on_fail);
     av_dict_free(&options);
     av_freep(&tmp_select);
     return ret;
@@ -380,6 +416,28 @@ static void log_slave(TeeSlave *slave, void *log_ctx, int log_level)
     }
 }
 
+static int tee_process_slave_failure(AVFormatContext *avf, unsigned slave_idx, int err_n)
+{
+    TeeContext *tee = avf->priv_data;
+    TeeSlave *tee_slave = &tee->slaves[slave_idx];
+
+    tee->nb_alive--;
+
+    close_slave(tee_slave);
+
+    if (!tee->nb_alive) {
+        av_log(avf, AV_LOG_ERROR, "All tee outputs failed.\n");
+        return err_n;
+    } else if (tee_slave->on_fail == ON_SLAVE_FAILURE_ABORT) {
+        av_log(avf, AV_LOG_ERROR, "Slave muxer #%u failed, aborting.\n", slave_idx);
+        return err_n;
+    } else {
+        av_log(avf, AV_LOG_ERROR, "Slave muxer #%u failed: %s, continuing with %u/%u slaves.\n",
+               slave_idx, av_err2str(err_n), tee->nb_alive, tee->nb_slaves);
+        return 0;
+    }
+}
+
 static int tee_write_header(AVFormatContext *avf)
 {
     TeeContext *tee = avf->priv_data;
@@ -403,19 +461,24 @@ static int tee_write_header(AVFormatContext *avf)
             filename++;
     }
 
-    tee->nb_slaves = nb_slaves;
+    tee->nb_slaves = tee->nb_alive = nb_slaves;
 
     for (i = 0; i < nb_slaves; i++) {
-        if ((ret = open_slave(avf, slaves[i], &tee->slaves[i])) < 0)
-            goto fail;
-        log_slave(&tee->slaves[i], avf, AV_LOG_VERBOSE);
+        if ((ret = open_slave(avf, slaves[i], &tee->slaves[i])) < 0) {
+            ret = tee_process_slave_failure(avf, i, ret);
+            if (ret < 0)
+                goto fail;
+        } else {
+            log_slave(&tee->slaves[i], avf, AV_LOG_VERBOSE);
+        }
         av_freep(&slaves[i]);
     }
 
     for (i = 0; i < avf->nb_streams; i++) {
         int j, mapped = 0;
         for (j = 0; j < tee->nb_slaves; j++)
-            mapped += tee->slaves[j].stream_map[i] >= 0;
+            if (tee->slaves[j].avf)
+                mapped += tee->slaves[j].stream_map[i] >= 0;
         if (!mapped)
             av_log(avf, AV_LOG_WARNING, "Input stream #%d is not mapped "
                    "to any slave.\n", i);
@@ -436,9 +499,11 @@ static int tee_write_trailer(AVFormatContext *avf)
     unsigned i;
 
     for (i = 0; i < tee->nb_slaves; i++) {
-        if ((ret = close_slave(&tee->slaves[i])) < 0)
-            if (!ret_all)
+        if ((ret = close_slave(&tee->slaves[i])) < 0) {
+            ret = tee_process_slave_failure(avf, i, ret);
+            if (!ret_all && ret < 0)
                 ret_all = ret;
+        }
     }
     return ret_all;
 }
@@ -454,7 +519,9 @@ static int tee_write_packet(AVFormatContext *avf, AVPacket *pkt)
     AVRational tb, tb2;
 
     for (i = 0; i < tee->nb_slaves; i++) {
-        avf2 = tee->slaves[i].avf;
+        if (!(avf2 = tee->slaves[i].avf))
+            continue;
+
         s = pkt->stream_index;
         s2 = tee->slaves[i].stream_map[s];
         if (s2 < 0)
@@ -475,9 +542,11 @@ static int tee_write_packet(AVFormatContext *avf, AVPacket *pkt)
 
         if ((ret = av_apply_bitstream_filters(avf2->streams[s2]->codec, &pkt2,
                                               tee->slaves[i].bsfs[s2])) < 0 ||
-            (ret = av_interleaved_write_frame(avf2, &pkt2)) < 0)
-            if (!ret_all)
+            (ret = av_interleaved_write_frame(avf2, &pkt2)) < 0) {
+            ret = tee_process_slave_failure(avf, i, ret);
+            if (!ret_all && ret < 0)
                 ret_all = ret;
+        }
     }
     return ret_all;
 }