fix(kvs/sink_gstreamer_sample): Use videotestsrc and add additional debug logging

[sirknightj]

Issue #, if available

When running the sample on a mac in live_source mode (./kvs_gstreamer_sample demo-stream), we would get "Elements could not be linked." error. We tested this on both m1 mac, and intel mac, each using GStreamer Core Library version 1.22.5 and encountered this error both times.

What was changed, and how was it changed?

• In live_source mode, use videotestsrc instead of autovideosrc
• Add additional debug logs
• The same was also applied to kvssink_gstreamer_sample, as these samples are very similar.
  • Fix typo in kvssink_gstreamer_sample: gracefully.

Why was it changed?

• We determined that data->h264_stream_supported is true, therefore, this pipeline was getting created.
• autovideosrc has ANY pads, so, when data.h264_stream_supported being determined, the intersection will always return true. autovideosrc's pads do not accurately reflect the available elements on the device, as that is determined during the application runtime. Both this if statement and this if statement return true with autovideosrc.
• Neither autovideosrc, videotestsrc or avfvideosrc output video/x-h264, therefore it cannot be directly linked to h264parse.
  • You can confirm this by using the following: gst-launch-1.0 <src element> ! capsfilter name=filter caps="video/x-h264" ! fakesink and seeing "WARNING: erroneous pipeline: could not link <src element> to filter". The application should be choosing to construct the top pipeline with the encoder element, rather than the bottom pipeline.
• By switching autovideosrc to videotestsrc, the correct caps are advertised, and the sample application (using gst_caps_can_intersect) is able to choose the correct pipeline to construct.

Testing

• Ran both samples in live source mode: ./kvs_gstreamer_sample demo-stream and ./kvssink_gstreamer_sample demo-stream and verified playback in the AWS management console.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.24% ⚠️

Comparison is base (4c4afff) 16.56% compared to head (7a088b8) 16.33%.

❗ Current head 7a088b8 differs from pull request most recent head 8df715a. Consider uploading reports for the commit 8df715a to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1047      +/-   ##
===========================================
- Coverage    16.56%   16.33%   -0.24%     
===========================================
  Files           51       51              
  Lines         6778     6844      +66     
===========================================
- Hits          1123     1118       -5     
- Misses        5655     5726      +71     

Files Changed	Coverage Δ
samples/kvs_gstreamer_sample.cpp	0.00% <0.00%> (ø)
samples/kvssink_gstreamer_sample.cpp	0.00% <0.00%> (ø)

... and 3 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[hassanctech]

Having gstreamer_life_source_init return 1 to indicate failure is fine. However I traced the code and found that this function is called inside gstreamer_init which is in turn called usually in main and in most cases it is called without checking the return value. Can we please correct all of those as well so we do not have silent failures.

amazon-kinesis-video-streams-producer-sdk-cpp/samples/kvs_gstreamer_sample.cpp

Line 1119 in e8125ee

gstreamer_init(argc, argv, &data);

amazon-kinesis-video-streams-producer-sdk-cpp/samples/kvs_gstreamer_sample.cpp

Line 1169 in e8125ee

gstreamer_init(argc, argv, &data);

[sirknightj]

Can we please correct all of those as well so we do not have silent failures.

Added.

[hassanctech]

lgtm