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Corona Radiata
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Lights in the Sky
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Mis à jour : Septembre 2011
Langue : English
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Langue : English
Type : Audio
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Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Letting You
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Mis à jour : Septembre 2011
Langue : English
Type : Audio
Autres articles (36)
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Des sites réalisés avec MediaSPIP
2 mai 2011, parCette page présente quelques-uns des sites fonctionnant sous MediaSPIP.
Vous pouvez bien entendu ajouter le votre grâce au formulaire en bas de page. -
Use, discuss, criticize
13 avril 2011, parTalk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
A discussion list is available for all exchanges between users. -
Contribute to a better visual interface
13 avril 2011MediaSPIP is based on a system of themes and templates. Templates define the placement of information on the page, and can be adapted to a wide range of uses. Themes define the overall graphic appearance of the site.
Anyone can submit a new graphic theme or template and make it available to the MediaSPIP community.
Sur d’autres sites (5352)
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How to get the first audio channel from a video with ffmpeg-python ?
31 mai 2022, par giskI would like to get the very first audio channel from a video using ffmpeg-python.


I tried with this :


out, _ = (
 ffmpeg
 .input(filename)
 .output('pipe:', loglevel=0, format='s16le', acodec='pcm_s16le', ac=1, ar='8k')
 .run(capture_stdout=True)
 )
 """ extract audio signal """
 self.signal = (
 np
 .frombuffer(out, np.int16) 
 )



but I am not sure whether this is correct.


I had a look here, but I could not find a solution : https://trac.ffmpeg.org/wiki/AudioChannelManipulation


Any suggestion ? Thanks !


EDIT :


I tried @rotem solution and it seems to work. However, I have another issue which seems related to the -ac flag. For some videos, the numpy output has the right length (i.e., it matches the original audio length). For others, I get a wrong one. However, if I set -ac to 2 for these videos, I get the correct signal length. Do you know why is this happening ?


This is the metadata of the video (duration : 2 minutes and 11 seconds) which outputs the correct numpy array size with setting -ac to 2


'streams' : ['index' : 0, 'codec_name' : 'h264', 'codec_long_name' : 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', 'profile' : 'High', 'codec_type' : 'video', 'codec_tag_string' : 'avc1', 'codec_tag' : '0x31637661', 'width' : 1920, 'height' : 1080, 'coded_width' : 1920, 'coded_height' : 1080, 'closed_captions' : 0, 'film_grain' : 0, 'has_b_frames' : 0, 'pix_fmt' : 'yuv420p', 'level' : 40, 'color_range' : 'tv', 'color_space' : 'bt709', 'color_transfer' : 'bt709', 'color_primaries' : 'bt709', 'chroma_location' : 'left', 'field_order' : 'progressive', 'refs' : 1, 'is_avc' : 'true', 'nal_length_size' : '4', 'id' : '0x1', 'r_frame_rate' : '30/1', 'avg_frame_rate' : '176805000/5894849', 'time_base' : '1/90000', 'start_pts' : 0, 'start_time' : '0.000000', 'duration_ts' : 11789698, 'duration' : '130.996644', 'bit_rate' : '16999840', 'bits_per_raw_sample' : '8', 'nb_frames' : '3929', 'extradata_size' : 34, 'disposition' : 'default' : 1, 'dub' : 0, 'original' : 0, 'comment' : 0, 'lyrics' : 0, 'karaoke' : 0, 'forced' : 0, 'hearing_impaired' : 0, 'visual_impaired' : 0, 'clean_effects' : 0, 'attached_pic' : 0, 'timed_thumbnails' : 0, 'captions' : 0, 'descriptions' : 0, 'metadata' : 0, 'dependent' : 0, 'still_image' : 0, 'tags' : 'creation_time' : '2022-05-30T15:00:39.000000Z', 'language' : 'eng', 'handler_name' : 'VideoHandle', 'vendor_id' : '[0][0][0][0]', 'index' : 1, 'codec_name' : 'aac', 'codec_long_name' : 'AAC (Advanced Audio Coding)', 'profile' : 'LC', 'codec_type' : 'audio', 'codec_tag_string' : 'mp4a', 'codec_tag' : '0x6134706d', 'sample_fmt' : 'fltp', 'sample_rate' : '48000', 'channels' : 2, 'channel_layout' : 'stereo', 'bits_per_sample' : 0, 'id' : '0x2', 'r_frame_rate' : '0/0', 'avg_frame_rate' : '0/0', 'time_base' : '1/48000', 'start_pts' : 696, 'start_time' : '0.014500', 'duration_ts' : 6285214, 'duration' : '130.941958', 'bit_rate' : '256004', 'nb_frames' : '6138', 'extradata_size' : 2, 'disposition' : 'default' : 1, 'dub' : 0, 'original' : 0, 'comment' : 0, 'lyrics' : 0, 'karaoke' : 0, 'forced' : 0, 'hearing_impaired' : 0, 'visual_impaired' : 0, 'clean_effects' : 0, 'attached_pic' : 0, 'timed_thumbnails' : 0, 'captions' : 0, 'descriptions' : 0, 'metadata' : 0, 'dependent' : 0, 'still_image' : 0, 'tags' : 'creation_time' : '2022-05-30T15:00:39.000000Z', 'language' : 'eng', 'handler_name' : 'SoundHandle', 'vendor_id' : '[0][0][0][0]'], 'format' : 'filename' : 'videos4/test_01.mp4', 'nb_streams' : 2, 'nb_programs' : 0, 'format_name' : 'mov,mp4,m4a,3gp,3g2,mj2', 'format_long_name' : 'QuickTime / MOV', 'start_time' : '0.000000', 'duration' : '130.996600', 'size' : '282621379', 'bit_rate' : '17259768', 'probe_score' : 100, 'tags' : 'major_brand' : 'mp42', 'minor_version' : '0', 'compatible_brands' : 'isommp42', 'creation_time' : '2022-05-30T15:00:39.000000Z', 'com.android.version' : '12', 'com.android.capture.fps' : '30.000000'.


This is instead, the metadata of the video (duration 5 minutes) which gives the right result length with setting -ac to 1 :


'streams' : ['index' : 0, 'codec_name' : 'h264', 'codec_long_name' : 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', 'profile' : 'High', 'codec_type' : 'video', 'codec_tag_string' : 'avc1', 'codec_tag' : '0x31637661', 'width' : 1920, 'height' : 1080, 'coded_width' : 1920, 'coded_height' : 1080, 'closed_captions' : 0, 'film_grain' : 0, 'has_b_frames' : 0, 'sample_aspect_ratio' : '1:1', 'display_aspect_ratio' : '16:9', 'pix_fmt' : 'yuv420p', 'level' : 40, 'field_order' : 'progressive', 'refs' : 1, 'is_avc' : 'true', 'nal_length_size' : '4', 'id' : '0x1', 'r_frame_rate' : '30/1', 'avg_frame_rate' : '33862500/1128779', 'time_base' : '1/90000', 'start_pts' : 0, 'start_time' : '0.000000', 'duration_ts' : 27090696, 'duration' : '301.007733', 'bit_rate' : '16999542', 'bits_per_raw_sample' : '8', 'nb_frames' : '9030', 'extradata_size' : 26, 'disposition' : 'default' : 1, 'dub' : 0, 'original' : 0, 'comment' : 0, 'lyrics' : 0, 'karaoke' : 0, 'forced' : 0, 'hearing_impaired' : 0, 'visual_impaired' : 0, 'clean_effects' : 0, 'attached_pic' : 0, 'timed_thumbnails' : 0, 'captions' : 0, 'descriptions' : 0, 'metadata' : 0, 'dependent' : 0, 'still_image' : 0, 'tags' : 'language' : 'und', 'handler_name' : 'VideoHandler', 'vendor_id' : '[0][0][0][0]', 'side_data_list' : ['side_data_type' : 'Display Matrix', 'displaymatrix' : '\n00000000 : 0 65536 0\n00000001 : -65536 0 0\n00000002 : 0 0 1073741824\n', 'rotation' : -90], 'index' : 1, 'codec_name' : 'aac', 'codec_long_name' : 'AAC (Advanced Audio Coding)', 'profile' : 'LC', 'codec_type' : 'audio', 'codec_tag_string' : 'mp4a', 'codec_tag' : '0x6134706d', 'sample_fmt' : 'fltp', 'sample_rate' : '48000', 'channels' : 2, 'channel_layout' : 'stereo', 'bits_per_sample' : 0, 'id' : '0x2', 'r_frame_rate' : '0/0', 'avg_frame_rate' : '0/0', 'time_base' : '1/48000', 'start_pts' : 0, 'start_time' : '0.000000', 'duration_ts' : 14448640, 'duration' : '301.013333', 'bit_rate' : '256000', 'nb_frames' : '14110', 'extradata_size' : 2, 'disposition' : 'default' : 1, 'dub' : 0, 'original' : 0, 'comment' : 0, 'lyrics' : 0, 'karaoke' : 0, 'forced' : 0, 'hearing_impaired' : 0, 'visual_impaired' : 0, 'clean_effects' : 0, 'attached_pic' : 0, 'timed_thumbnails' : 0, 'captions' : 0, 'descriptions' : 0, 'metadata' : 0, 'dependent' : 0, 'still_image' : 0, 'tags' : 'language' : 'und', 'handler_name' : 'SoundHandler', 'vendor_id' : '[0][0][0][0]'], 'format' : 'filename' : 'videos4/video_02.mp4', 'nb_streams' : 2, 'nb_programs' : 0, 'format_name' : 'mov,mp4,m4a,3gp,3g2,mj2', 'format_long_name' : 'QuickTime / MOV', 'start_time' : '0.000000', 'duration' : '301.014000', 'size' : '649577064', 'bit_rate' : '17263703', 'probe_score' : 100, 'tags' : 'major_brand' : 'isom', 'minor_version' : '512', 'compatible_brands' : 'isomiso2avc1mp41', 'encoder' : 'Lavf58.27.103'


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Google Analytics Privacy Issues : Is It Really That Bad ?
2 juin 2022, par Erin -
Can't show image with opencv when importing av
5 mars, par FlojomojoWhen importing the PyAv module, I am unable to show an image with opencv using imshow()


Code without the PyAv module (works as expected)


import cv2

img = cv2.imread("test_image.jpeg")
cv2.imshow('image', img)
cv2.waitKey(0)



Code with the import (doesn't work, just hangs)


import cv2
import av

img = cv2.imread("test_image.jpeg")
cv2.imshow('image', img)
cv2.waitKey(0)



OS : Linux arch 5.18.3-arch1-1 #1 SMP PREEMPT_DYNAMIC Thu, 09 Jun 2022 16:14:10 +0000 x86_64 GNU/Linux


Am I doing something wrong or is this a (un-)known issue ?