[BUG] AWS kvssink shall not crash when providing pipeline with H265 encoding.

[sbelbin]

Logging

0:00:02.458971542 �[34m 1257�[00m    0x3024d21c0 �[37mDEBUG  �[00m �[00mGStreamerSwiftUIDemo GStreamerBackend.m:192:-[GStreamerBackend run_app_pipeline]:�[00m Creating pipeline
0:00:02.460718584 �[34m 1257�[00m    0x3024d21c0 �[31;01mERROR  �[00m �[00;01;37;41m        GST_PIPELINE gst/parse/grammar.y:1134:gst_parse_perform_link:�[00m could not link vtenc_h265-0 to kvssink0, vtenc_h265-0 can't handle caps video/x-h265, stream-format=(string)avc, alignment=(string)au, profile=(string)baseline
[INFO ] [16-12-2024 20:21:40:636.289 UTC] Logger config being used: /var/mobile/Containers/Data/Application/**********************/Documents/aws-kvs-log.cfg
[INFO ] [16-12-2024 20:21:40:636.611 UTC] User agent string: AWS-SDK-KVS-CPP-CLIENT/3.4.2
[INFO ] [16-12-2024 20:21:40:646.267 UTC] createKinesisVideoClient(): Creating Kinesis Video Client
[TRACE] [16-12-2024 20:21:40:646.439 UTC] normalizeExponentialBackoffConfig(): Thread Id [6170980352]. Exponential backoff retry strategy config - maxRetryCount: [0], maxRetryWaitTime: [100000000], retryFactorTime: [1000000], minTimeToResetRetryState: [900000000], jitterType: [1], jitterFactor: [0], 
[TRACE] [16-12-2024 20:21:40:646.491 UTC] resetExponentialBackoffRetryState(): Thread Id [6170980352]. Resetting Exponential Backoff State. Last retry system time [0], retry count so far [0], Current system time [17343805006464890]
[TRACE] [16-12-2024 20:21:40:646.559 UTC] exponentialBackoffRetryStrategyCreate(): Created exponential backoff retry strategy state with provided retry configuration.
[INFO ] [16-12-2024 20:21:40:646.621 UTC] heapInitialize(): Initializing native heap with limit size 134217728, spill ratio 0% and flags 0x00000001
[INFO ] [16-12-2024 20:21:40:646.661 UTC] heapInitialize(): Creating AIV heap.
[INFO ] [16-12-2024 20:21:40:646.739 UTC] heapInitialize(): Heap is initialized OK
[TRACE] [16-12-2024 20:21:40:646.892 UTC] stepStateMachine(): [CLIENT] State Machine - Current state: 0x0000000000000001, Next state: 0x0000000000000002, Current local state retry count [0], Max local state retry count [5], State transition wait time [0] ms
[DEBUG] [16-12-2024 20:21:40:646.943 UTC] getSecurityTokenHandler invoked
[DEBUG] [16-12-2024 20:21:40:646.986 UTC] Refreshing credentials. Force refreshing: 0 Now time is: 1734380500646978 Expiration: 0
[TRACE] [16-12-2024 20:21:40:647.052 UTC] stepStateMachine(): [CLIENT] State Machine - Current state: 0x0000000000000002, Next state: 0x0000000000000010, Current local state retry count [0], Max local state retry count [5], State transition wait time [0] ms
[INFO ] [16-12-2024 20:21:40:647.129 UTC] createDeviceResultEvent(): Create device result event.
[TRACE] [16-12-2024 20:21:40:647.195 UTC] stepStateMachine(): [CLIENT] State Machine - Current state: 0x0000000000000010, Next state: 0x0000000000000040, Current local state retry count [0], Max local state retry count [0], State transition wait time [0] ms
[DEBUG] [16-12-2024 20:21:40:647.235 UTC] clientReadyHandler invoked
[TRACE] [16-12-2024 20:21:40:647.269 UTC] createKinesisVideoClientSync(): Awaiting for the Kinesis Video Client to become ready...
[TRACE] [16-12-2024 20:21:40:647.300 UTC] createKinesisVideoClientSync(): Kinesis Video Client is Ready.

Describe the bug
When running a sample app running on an iPad device where the pipeline passed to GStreamer is the following:

"avfvideosrc ! video/x-raw, width=1280, height=720, framerate=30/1 ! videoconvert ! vtenc_h265 ! video/x-h265, stream-format=avc, alignment=au, profile=baseline ! kvssink stream-name=neuroservo-sbelbin-test storage-size=128 aws-region=%s access-key=%s secret-key=%s log-config=%s"

This results in the kvssink GStreamer plugin causing an app crash with a BAD_ACCESS due to a null reference access when transitiioning to a PLAY state.

Expected behavior
Although there is an error the pipeline still this shall not result in a BAD_ACCESS exception from the kvssink plugin later on. Instead it shall gracefully error and ideally report that the operation cannot be performed due to unsupported encoding in the pipeline.

0:00:02.460718584 �[34m 1257�[00m    0x3024d21c0 �[31;01mERROR  �[00m �[00;01;37;41m        GST_PIPELINE gst/parse/grammar.y:1134:gst_parse_perform_link:�[00m could not link vtenc_h265-0 to kvssink0, vtenc_h265-0 can't handle caps video/x-h265, stream-format=(string)avc, alignment=(string)au, profile=(string)baseline

SDK version number
Using the source code from master branch.

Open source building

• Built using iOS SDK
• Everything is built as a static library, since deployment of GStreamer for iOS expects plugins as static libraries.

Screenshots
N/A

Platform (please complete the following information):

• OS: iOS
• Processor: ARM64
• Version iOS 18.2

Additional context

The crash is at this line of code is in the init_track_data function gstkvssink.c when the return of calling the gst_pad_get_allowed_caps returns a NULL value into the caps variable.

Since the code lacks to verify if that variable is NULL, then the subsequent will eventually result in a BAD_ACCESS failure. The code needs to check for NULL and take the appropriate actions.

    for (walk = kvssink->collect->data; walk != NULL; walk = g_slist_next (walk)) {
        GstKvsSinkTrackData *kvs_sink_track_data = (GstKvsSinkTrackData *) walk->data;

        if (kvs_sink_track_data->track_type == MKV_TRACK_INFO_TYPE_VIDEO) {

            if (kvssink->data->media_type == AUDIO_VIDEO) {
                kvs_sink_track_data->track_id = KVS_SINK_DEFAULT_TRACKID;
            }

            GstCollectData *collect_data = (GstCollectData *) walk->data;

            // extract media type from GstCaps to check whether it's h264 or h265
            caps = gst_pad_get_allowed_caps(collect_data->pad);
            media_type = gst_structure_get_name(gst_caps_get_structure(caps, 0));
            if (strncmp(media_type, GSTREAMER_MEDIA_TYPE_H264, MAX_GSTREAMER_MEDIA_TYPE_LEN) == 0) {
                // default codec id is for h264 video.
                video_content_type = g_strdup(MKV_H264_CONTENT_TYPE);
            } else if (strncmp(media_type, GSTREAMER_MEDIA_TYPE_H265, MAX_GSTREAMER_MEDIA_TYPE_LEN) == 0) {
                g_free(kvssink->codec_id);
                kvssink->codec_id = g_strdup(DEFAULT_CODEC_ID_H265);
                video_content_type = g_strdup(MKV_H265_CONTENT_TYPE);
            } else {
                // no-op, should result in a caps negotiation error before getting here.
                LOG_AND_THROW("Error, media type " << media_type << "not accepted by kvssink" << " for " << kvssink->stream_name);
            }
            gst_caps_unref(caps);

        } else if (kvs_sink_track_data->track_type == MKV_TRACK_INFO_TYPE_AUDIO) {

[stefankiesz]

Hi Steven, thank you very much for all your work on this kvssink-iOS integration and details shared along the way.

I confirmed per GStreamer documentation, gst_pad_get_allowed_caps "returns NULL when pad has no peer." I'll put out a fix for this shortly.