Sur d’autres sites (11108)

• What is the bitrate of my audio file based on ffmpeg output ?

  21 avril 2015, par blueether

  Is it the 40kb/s under Format, or is it the 16kb/s under Stream ? What is the relationship between the Format and the Stream ?
  The below output is for a file generated using Core Audio on an iphone, with an Audio Unit. The output format was specified by an AudioStreamBasicDescription descriptor

  Updated :
  Output from ffprobe -v error -show_format -show_streams 123_1429602551009.051025.m4a :

  [STREAM]
  
  index=0
  
  codec_name=aac
  
  codec_long_name=AAC (Advanced Audio Coding)
  
  profile=LC
  
  codec_type=audio
  
  codec_time_base=1/8000
  
  codec_tag_string=mp4a
  
  codec_tag=0x6134706d
  
  sample_fmt=fltp
  
  sample_rate=8000
  
  channels=1
  
  channel_layout=mono
  
  bits_per_sample=0
  
  id=N/A
  
  r_frame_rate=0/0
  
  avg_frame_rate=0/0
  
  time_base=1/8000
  
  start_pts=0
  
  start_time=0.000000
  
  duration_ts=43008
  
  duration=5.376000
  
  bit_rate=16501
  
  max_bit_rate=N/A
  
  bits_per_raw_sample=N/A
  
  nb_frames=42
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  DISPOSITION:default=1
  
  DISPOSITION:dub=0
  
  DISPOSITION:original=0
  
  DISPOSITION:comment=0
  
  DISPOSITION:lyrics=0
  
  DISPOSITION:karaoke=0
  
  DISPOSITION:forced=0
  
  DISPOSITION:hearing_impaired=0
  
  DISPOSITION:visual_impaired=0
  
  DISPOSITION:clean_effects=0
  
  DISPOSITION:attached_pic=0
  
  TAG:creation_time=1970-04-16 22:36:01
  
  TAG:language=eng
  
  [/STREAM]
  
  [FORMAT]
  
  filename=123_1429602551009.051025.m4a
  
  nb_streams=1
  
  nb_programs=0
  
  format_name=mov,mp4,m4a,3gp,3g2,mj2
  
  format_long_name=QuickTime / MOV
  
  start_time=0.000000
  
  duration=5.376000
  
  size=27473
  
  bit_rate=40882
  
  probe_score=100
  
  TAG:major_brand=M4A
  
  TAG:minor_version=0
  
  TAG:compatible_brands=M4A mp42isom
  
  TAG:creation_time=1970-04-16 22:36:01
  
  TAG:iTunSMPB= 00000000 00000840 00000361 0000000000009C5F 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
  
  [/FORMAT]

• Safari sends excessive HTTP range requests during HTML5 MOV playback

  28 mai, par Lucy

  I am currently developing a web application based on React and Next.js, and I use the react-player library to play user-uploaded videos stored on AWS S3. The supported upload video formats are mp4, mov, and mkv, with codecs including H.264 or H.265 (HEVC).

  


  Problem

  


  However, some H.264 videos in the mov format exhibit noticeably poor playback performance only in the Safari browser. The videos do not play smoothly and frequently experience stuttering or delays.

  


  How Safari Handles Range Requests (As I Understand It) :

  


  

  1. Safari first sends a normal GET request to check if the server supports Range requests. If the server responds with the header Accept-Ranges : bytes, Safari closes the connection.

  


  2. Then, Safari sends a very small range request like Range : bytes=0-1 to confirm it receives a 206 Partial Content response.

  


  3. Next, Safari requests some parts from the beginning and the end of the file to locate metadata such as the moov atom in MP4 files.

  


  4. After that, actual streaming begins, but Safari does not request the entire file at once ; instead, it divides the needed parts into multiple small Range requests.

  


  


  Example of Actual Problematic Requests

  


  Below are some of the Range requests Safari makes for the problematic .mov video (H.264 codec) :

  


  # Request - 1
Connection: keep-alive
Range: bytes=0-1

# Response
HTTP/1.1 206 Partial Content
Accept-Ranges: bytes
Content-Disposition: attachment;filename*=utf-8''test.mov
Content-Length: 2
Content-Range: bytes 0-1/102801747
Content-Type: video/quicktime

-------------------------------------
# Request - 2
Connection: Keep-Alive
Range: bytes=0-102801746

# Response
HTTP/1.1 206 Partial Content
Accept-Ranges: bytes
Content-Disposition: attachment;filename*=utf-8''test.mov
Content-Length: 102801747
Content-Range: bytes 0-102801746/102801747
Content-Type: video/quicktime

-------------------------------------
# Request - 3
Connection: Keep-Alive
Range: bytes=102760448-102801746

# Response - 3
HTTP/1.1 206 Partial Content
Accept-Ranges: bytes
Content-Disposition: attachment;filename*=utf-8''test.mov
Content-Length: 41299
Content-Range: bytes 102760448-102801746/102801747
Content-Type: video/quicktime

-------------------------------------
# Request - 4
Connection: keep-alive
Range: bytes=3014656-3080191 # 64KB

# Response - 4
HTTP/1.1 206 Partial Content
Accept-Ranges: bytes
Content-Disposition: attachment;filename*=utf-8''IMG_7929.mov
Content-Length: 65536
Content-Range: bytes 3014656-3080191/102801747
Content-Type: video/quicktime


  


  Safari continues to send hundreds of similar small Range requests repeatedly, gradually downloading the file.

  


  This causes increased network load, which ultimately leads to video stuttering or playback delays.

  


  Example of another .mov file that works properly :

  


  In contrast, another .mov video using the same format and codec (H.264) sends Range requests over much larger byte ranges, downloading about 30MB of data at once. In this case, the video plays smoothly.

  


  # Request 
Connection: Keep-Alive
Range: bytes=1310534-673918954 # Request : 672MB, Actual Downloaded : 32MB

# Response
Accept-Ranges: bytes
Content-Disposition: attachment;filename*=utf-8''mov-example-video-download-4k-uhd-3840x2160.mov
Content-Length: 672608421
Content-Range: bytes 1310534-673918954/673918955
Content-Type: video/quicktime


  


  Question

  


  In Safari, for certain video files, the browser repeatedly closes the connection after receiving only a few kilobytes per request and immediately sends the next request. As a result, dozens or even hundreds of small range requests occur consecutively. This causes increased connection overhead and latency, and although the web server can deliver data at sufficient speed, the player does not receive data in time, leading to poor and stuttering video playback.

  


  

  1. What could be the reason Safari repeatedly makes these very small requests for certain files ?

  


  2. Could the internal structure of the video file (such as the moov atom) influence this request pattern ?

  


  


  f you have any similar experience or advice, please share.

  


  What I'ved tried

  


  

  • Using ffmpeg to move the moov atom to the beginning of the file with -movflags faststart does not resolve the issue — the same problem persists.

  


  • Converting the exact same video to MP4 format and testing it results in normal playback without issues.

  


  


  Test Environment

  


  

  • Macbook pro 16

  


  • mac OS - Sequoia 15.5

  


  • Safari - Latest

  


  


  File information

  


  Due to company policy, I am unable to share the problematic video files directly. However, I am attaching the file information obtained via ffprobe for your reference.

  


  ffprobe -v error -show_format -show_streams -print_format json test.mov

{
    "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": 3840,
            "height": 2160,
            "coded_width": 3840,
            "coded_height": 2160,
            "closed_captions": 0,
            "film_grain": 0,
            "has_b_frames": 0,
            "pix_fmt": "yuv420p",
            "level": 51,
            "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": "30000/1001",
            "avg_frame_rate": "18200/607",
            "time_base": "1/600",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 10925,
            "duration": "18.208333",
            "bit_rate": "44900923",
            "bits_per_raw_sample": "8",
            "nb_frames": "546",
            "extradata_size": 158,
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Video",
                "vendor_id": "[0][0][0][0]",
                "encoder": "H.264"
            }
        },
        {
            "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": "44100",
            "channels": 2,
            "channel_layout": "stereo",
            "bits_per_sample": 0,
            "initial_padding": 0,
            "id": "0x2",
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/44100",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 802988,
            "duration": "18.208345",
            "bit_rate": "187218",
            "nb_frames": "787",
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Audio",
                "vendor_id": "[0][0][0][0]"
            }
        },
        {
            "index": 2,
            "codec_type": "data",
            "codec_tag_string": "mebx",
            "codec_tag": "0x7862656d",
            "id": "0x3",
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/600",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 10925,
            "duration": "18.208333",
            "bit_rate": "4",
            "nb_frames": "1",
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Metadata"
            }
        },
        {
            "index": 3,
            "codec_type": "data",
            "codec_tag_string": "mebx",
            "codec_tag": "0x7862656d",
            "id": "0x4",
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/600",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 10925,
            "duration": "18.208333",
            "bit_rate": "6756",
            "nb_frames": "80",
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Metadata"
            }
        },
        {
            "index": 4,
            "codec_type": "data",
            "codec_tag_string": "mebx",
            "codec_tag": "0x7862656d",
            "id": "0x5",
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/600",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 10925,
            "duration": "18.208333",
            "bit_rate": "50764",
            "nb_frames": "546",
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Metadata"
            }
        },
        {
            "index": 5,
            "codec_type": "data",
            "codec_tag_string": "mebx",
            "codec_tag": "0x7862656d",
            "id": "0x6",
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/600",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 10925,
            "duration": "18.208333",
            "bit_rate": "19",
            "nb_frames": "1",
            "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,
                "non_diegetic": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0,
                "multilayer": 0
            },
            "tags": {
                "creation_time": "",
                "language": "und",
                "handler_name": "Core Media Metadata"
            }
        }
    ],
    "format": {
        "filename": "test.mov",
        "nb_streams": 6,
        "nb_programs": 0,
        "nb_stream_groups": 0,
        "format_name": "mov,mp4,m4a,3gp,3g2,mj2",
        "format_long_name": "QuickTime / MOV",
        "start_time": "0.000000",
        "duration": "18.208345",
        "size": "102801747",
        "bit_rate": "45166871",
        "probe_score": 100,
        "tags": {
            "major_brand": "qt  ",
            "minor_version": "0",
            "compatible_brands": "qt  ",
            "creation_time": "",
            "com.apple.quicktime.location.accuracy.horizontal": "76.200233",
            "com.apple.quicktime.full-frame-rate-playback-intent": "0",
            "com.apple.quicktime.location.ISO6709": "",
            "com.apple.quicktime.make": "Apple",
            "com.apple.quicktime.model": "iPhone 15 Pro",
            "com.apple.quicktime.software": "18.4.1",
            "com.apple.quicktime.creationdate": ""
        }
    }
}


  


• lavu/tx : improve 3-point fixed precision

  14 février 2020, par Lynne

  lavu/tx : improve 3-point fixed precision
  There's just no reason not to when its so easy (albeit messy) and its also
  
  reducing the precision of all non-power-of-two transforms that use it.
  

  • [DH] libavutil/tx_priv.h
  • [DH] libavutil/tx_template.c