23 lines
1.7 KiB
Python
23 lines
1.7 KiB
Python
import subprocess,json,array,wave,math
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from pathlib import Path
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D=Path(__file__).resolve().parent
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p=D/'out/TTREE-30s.mp4'
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def run(args):return subprocess.check_output(args)
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info=json.loads(run(['ffprobe','-v','error','-show_streams','-show_format','-of','json',str(p)]))
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v=next(x for x in info['streams'] if x['codec_type']=='video')
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a=next(x for x in info['streams'] if x['codec_type']=='audio')
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# Decode all frames at analysis resolution; compare seam against adjacent motion.
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raw=run(['ffmpeg','-v','error','-i',str(p),'-vf','scale=192:108','-f','rawvideo','-pix_fmt','gray','-'])
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size=192*108; frames=[raw[i:i+size] for i in range(0,len(raw),size)]
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def mae(a,b):return sum(abs(x-y) for x,y in zip(a,b))/len(a)
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# Decode delivery AAC as well as original PCM; assess boundary sample jump.
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sound=array.array('f',run(['ffmpeg','-v','error','-i',str(p),'-vn','-f','f32le','-ar','48000','-ac','2','-']))
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jump=max(abs(sound[c]-sound[-2+c]) for c in [0,1])
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peak=max(abs(x) for x in sound)
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black=[i for i,x in enumerate(frames) if sum(x)/len(x)<10]
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result={'duration_seconds':float(info['format']['duration']),'width':v['width'],'height':v['height'],'fps':v['r_frame_rate'],'frames':len(frames),'audio_codec':a['codec_name'],'audio_hz':a['sample_rate'],'black_frames':black,'seam_mean_pixel_delta_255':mae(frames[-1],frames[0]),'adjacent_start_delta':mae(frames[0],frames[1]),'adjacent_end_delta':mae(frames[-2],frames[-1]),'aac_peak_linear':peak,'aac_boundary_jump_linear':jump,'aac_boundary_jump_dbfs':20*math.log10(max(jump,1e-12))}
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assert len(frames)==900 and not black and abs(result['duration_seconds']-30)<.001
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assert jump<.01 and peak<1
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(D/'out/qa.json').write_text(json.dumps(result,indent=2))
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print(json.dumps(result,indent=2))
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