# GST\_MESSAGE\_DURATION\_CHANGED failure **URL:** \ **Category:** Newcomers\ **Created:** [August 28, 2024, 12:12pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270 "2024-08-28T12:12:55Z")\ **Posts on this page:** 5\ **Page:** 1

**Author:** ![sechshelme](https://discourse.gstreamer.org/user_avatar/discourse.gstreamer.org/sechshelme/32/739_2.png) [@sechshelme](https://discourse.gstreamer.org/u/sechshelme)\ **Post date:** [August 28, 2024, 12:12pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270/1 "2024-08-28T12:12:55Z")

Why doesn’t the message `GST_MESSAGE_DURATION_CHANGED` arrive with this code? Other messages like `GST_MESSAGE_STATE_CHANGED` arrive. ```auto // gcc main.c -o main `pkg-config --cflags --libs gstreamer-1.0 gstreamer-audio-1.0` #include int quit = 0; static void test_cb(GstBus *bus, GstMessage *msg, gpointer data) { g_print("Message: %i\n", msg); switch (GST_MESSAGE_TYPE(msg)) { case GST_MESSAGE_DURATION_CHANGED: g_print("Duration changed\n"); break; case GST_MESSAGE_STATE_CHANGED: g_print("State changed\n"); break; case GST_MESSAGE_EOS: g_print("Finish\n"); quit = 1; break; } } int main(int argc, char *argv[]) { gst_init(&argc, &argv); GstElement *pipeline = gst_parse_launch("filesrc location=/home/tux/Schreibtisch/sound/test.wav ! decodebin ! audioconvert ! autoaudiosink", NULL); GstBus *bus = gst_element_get_bus(pipeline); gst_bus_add_signal_watch(bus); g_signal_connect(bus, "message", G_CALLBACK(test_cb), NULL); gst_object_unref(bus); gst_element_set_state(pipeline, GST_STATE_PLAYING); while (!quit) { g_main_context_iteration(0, 0); } } ``` ---

**Author:** ![Honey\_Patouceul](https://discourse.gstreamer.org/user_avatar/discourse.gstreamer.org/honey_patouceul/32/365_2.png) [@Honey\_Patouceul](https://discourse.gstreamer.org/u/Honey_Patouceul)\ **Post date:** [August 28, 2024, 7:37pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270/2 "2024-08-28T19:37:05Z")

Not sure, but as you’re playing a single file with a fixed duration, I wouldn’t expect that message to be issued. I might be wrong, someone better skilled may correct my assumption. ---

**Author:** ![sechshelme](https://discourse.gstreamer.org/user_avatar/discourse.gstreamer.org/sechshelme/32/739_2.png) [@sechshelme](https://discourse.gstreamer.org/u/sechshelme)\ **Post date:** [August 29, 2024, 3:15pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270/3 "2024-08-29T15:15:18Z")

> Not sure, but as you’re playing a single file with a fixed duration, I wouldn’t expect that message to be issued.[/quote] It seems that Duration does not appear for every file type. It does not appear for WAV, but it does appear for FLAC and MP3. wav: ```auto Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-start Message: latency Message: tag Message: state-changed Message: state-changed Message: state-changed Message: async-done Message: latency Message: new-clock Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed ``` Flac: ```auto Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: duration-changed Message: state-changed Message: state-changed Message: latency Message: state-changed Message: stream-start Message: latency Message: tag Message: state-changed Message: state-changed Message: state-changed Message: async-done Message: latency Message: new-clock Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag Message: tag ``` MP3: ```auto Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: stream-status Message: state-changed Message: state-changed Message: state-changed Message: stream-start Message: latency Message: tag Message: tag Message: state-changed Message: state-changed Message: state-changed Message: async-done Message: latency Message: new-clock Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: state-changed Message: tag Message: tag Message: duration-changed ``` Addendum: OGG doesn’t work either. Is there a way I can get the duration for WAV and OGG? ---

**Author:** ![Honey\_Patouceul](https://discourse.gstreamer.org/user_avatar/discourse.gstreamer.org/honey_patouceul/32/365_2.png) [@Honey\_Patouceul](https://discourse.gstreamer.org/u/Honey_Patouceul)\ **Post date:** [August 29, 2024, 7:00pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270/4 "2024-08-29T19:00:12Z")

Ok, got it. Someone more skilled may provide more accurate advice for this case… In the meantime, do you see differences from gst-discoverer-1.0 for the various cases ? ---

**Author:** ![tpm](https://discourse.gstreamer.org/letter_avatar_proxy/v4/letter/t/c5a1d2/32.png) [@tpm](https://discourse.gstreamer.org/u/tpm)\ **Post date:** [August 31, 2024, 2:22pm UTC](https://discourse.gstreamer.org/t/gst-message-duration-changed-failure/2270/5 "2024-08-31T14:22:45Z")

If you’re just interested in the duration, you would usually just do a duration query it when you get an `ASYNC_DONE` message on the bus (which is when the pipeline is prerolled, at which point the demuxer/parsers will have produced some data and will have processed headers and metadata). The `DURATION_CHANGED` message on the bus is something elements can post to indicate to the application that something has changed and it should re-query the duration. With most container formats, the duration is determined and known initially once the headers have been processed. The main case where you get a `DURATION_CHANGED` message is with audio files that are elementary streams without a container, such as e.g. MP3, where in case of VBR encoding the parser will update the duration estimate over time, as the estimated average bitrate changes the more frames it processes, which means the duration estimate in time will change too (but depends on what other metadata exists, e.g. there could be xing metadata or such to provide good info from the start). Long story short: don’t expect a `DURATION_CHANGED` message from the start, just query the duration yourself and then query again when you get a message that says that it changed.