Encode YUV420 buffer with appsrc

[Antonio Ospite]

On Tue, 10 Oct 2017 11:25:58 -0700 (MST)
pchaurasia <pchaurasia at gameloreinc.com> wrote:

> Thanks Nicolas, for all the help.
> 
> I wrote a small stand alone code to make simple encoder pipeline driven by
> appsrc. I think I followed all aforementioned suggestions from you. 
>

With a test program it is easier to discuss.

If I may add a side note, it is possible to make the test program more
concise by using gst_parse_launch() to build the pipeline and retrieving
the app source with gst_bin_get_by_name(); something like:

data.pipeline = gst_parse_launch
    ("appsrc name=audio_source ! ... ! filesink location=test1.mp4",
     NULL);
data.app_source =
  gst_bin_get_by_name (GST_BIN (data.pipeline), "sound_source");

When asking for help try to provide the *minimum* program you can come
up with which still reproduces your problem.

> I am able to run it. I do get a compressed video file (test1.mp4), however,
> that file does not have much other than headers. I tried to play it using
> mplayer and it would not play. I think, I am missing something. Would be
> great if you could give a look to my code to spot the problem.

The problem seems to be about buffer timestamps, the buffers are created
successfully (you can verify that with this pipeline:

  "appsrc name=audio_source ! fakesink dump=1"
  
but then they are discarded, presumably because they have invalid
timestamps.

The following patch is just a proof-of-concept which produces a valid
encoded video (note that I had to change some headers and use x264enc on
my system):

$ diff -pruN main.cpp.orig main.cpp
--- main.cpp.orig	2017-10-10 23:15:30.185947947 +0200
+++ main.cpp	2017-10-10 23:33:50.467881200 +0200
@@ -9,11 +9,9 @@
 #include <string.h>
 
 
-#include "opencv2/imgcodecs.hpp"
-#include "opencv2/imgproc.hpp"
-#include "opencv2/videoio.hpp"
-#include <opencv2/highgui.hpp>
-#include <opencv2/video.hpp>
+#include "opencv2/imgproc/imgproc.hpp"
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/video/video.hpp>
 
 
 #include <iostream>
@@ -158,6 +156,8 @@ static void start_feed (GstElement *sour
     //ref buffer to give copy to appsrc
     gst_buffer_ref(m_pgstBuffer);
 
+    GST_BUFFER_DTS (m_pgstBuffer) = 0;
+    GST_BUFFER_PTS (m_pgstBuffer) = 0;
 
     g_print ("Signalling push-buffer with new buffer\n");
 
@@ -253,7 +253,7 @@ main (int argc, char * argv[])
   data.app_source             = gst_element_factory_make ("appsrc", "audio_source");
   //data.app_sink               = gst_element_factory_make ("appsink", "app_sink");
   data.m_pvideoConvert        = gst_element_factory_make("autovideoconvert", "aa-videoconvert");
-  data.m_pencoder             = gst_element_factory_make("omxh265enc", "aa-videoencoder");
+  data.m_pencoder             = gst_element_factory_make("x264enc", "aa-videoencoder");
   data.m_pmux                 = gst_element_factory_make("matroskamux", "aa-mux");
   data.m_pfsink               = gst_element_factory_make("filesink", "aa-filesink");
   data.sourceid               = 0; 
@@ -285,6 +285,8 @@ main (int argc, char * argv[])
   g_signal_connect (data.app_source, "need-data", G_CALLBACK (start_feed), &data);
   g_signal_connect (data.app_source, "enough-data", G_CALLBACK (stop_feed), &data);
 
+  g_object_set (data.app_source, "format", GST_FORMAT_TIME, NULL);
+
 
   /* Configure appsink */
   //g_object_set (data.app_sink, "emit-signals", TRUE, "caps", caps, NULL);


The final result may still not be "correct", tho.

Ciao,
   Antonio

-- 
Antonio Ospite
https://ao2.it
https://twitter.com/ao2it

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