diff --git a/common/common/segments.py b/common/common/segments.py index c81cee8..7790225 100644 --- a/common/common/segments.py +++ b/common/common/segments.py @@ -587,3 +587,56 @@ def render_segments_waveform(segments, size=(1024, 128), scale='sqrt', color='#0 except (OSError, IOError): pass + +@timed('extract_frame') +def extract_frame(segments, timestamp): + """ + Extract the frame at TIMESTAMP within SEGMENT, yielding it as chunks of PNG data. + """ + + # Remove holes + segments = [segment for segment in segments if segment is not None] + + # Find segment containing timestamp + segments = [ + segment for segment in segments + if segment.start <= timestamp < segment.end + ] + if not segments: + raise ValueError("No data at timestamp within segment list") + if len(segments) != 1: + raise ValueError("Segment list contains overlap at timestamp") + (segment,) = segments + + # "cut" input so that first frame is our target frame + cut_start = (timestamp - segment.start).total_seconds() + + ffmpeg = None + input_feeder = None + try: + args = [ + # get a single frame + '-vframes', '1', + # output as png + '-f', 'image2', '-c', 'png', + ] + ffmpeg = ffmpeg_cut_stdin(subprocess.PIPE, cut_start=cut_start, duration=None, encode_args=args) + input_feeder = gevent.spawn(feed_input, segments, ffmpeg.stdin) + + for chunk in read_chunks(ffmpeg.stdout): + yield chunk + + # check if any errors occurred in input writing, or if ffmpeg exited non-success. + if ffmpeg.wait() != 0: + raise Exception("Error while extracting frame: ffmpeg exited {}".format(ffmpeg.returncode)) + input_feeder.get() # re-raise any errors from feed_input() + finally: + # if something goes wrong, try to clean up ignoring errors + if input_feeder is not None: + input_feeder.kill() + if ffmpeg is not None and ffmpeg.poll() is None: + for action in (ffmpeg.kill, ffmpeg.stdin.close, ffmpeg.stdout.close): + try: + action() + except (OSError, IOError): + pass diff --git a/restreamer/restreamer/main.py b/restreamer/restreamer/main.py index 5269693..4706810 100644 --- a/restreamer/restreamer/main.py +++ b/restreamer/restreamer/main.py @@ -16,7 +16,7 @@ from gevent.pywsgi import WSGIServer from common import dateutil, get_best_segments, rough_cut_segments, fast_cut_segments, full_cut_segments, PromLogCountsHandler, install_stacksampler, serve_with_graceful_shutdown from common.flask_stats import request_stats, after_request -from common.segments import feed_input, render_segments_waveform +from common.segments import feed_input, render_segments_waveform, extract_frame from . import generate_hls @@ -356,6 +356,29 @@ def generate_waveform(channel, quality): return Response(render_segments_waveform(segments, (width, height)), mimetype='image/png') +@app.route('/frame//.png') +@request_stats +@has_path_args +def get_frame(channel, quality): + """ + Returns a PNG image for the frame at the specific timestamp given. + Params: + timestamp: Required. The timestamp to get. + Must be in ISO 8601 format (ie. yyyy-mm-ddTHH:MM:SS) and UTC. + """ + timestamp = dateutil.parse_utc_only(request.args['timestamp']) + + hours_path = os.path.join(app.static_folder, channel, quality) + if not os.path.isdir(hours_path): + abort(404) + + segments = get_best_segments(hours_path, timestamp, timestamp) + if not any(segment is not None for segment in segments): + return "We have no content available within the requested time range.", 406 + + return Response(extract_frame(segments, timestamp), mimetype='image/png') + + @app.route('/generate_videos//', methods=['POST']) @request_stats @has_path_args