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• 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": ""
        }
    }
}


  


• How to set reference frame to 1 while using ffmpeg with h264_videotoolbox encoder

  23 février 2024, par RockyAo

  ffmpeg verison 6.0.1
codec : "h264_videotoolbox"

  


  I tried to set codec context's ref to 1, but it's not working. also I tried to set gop_size to 2, same result. An iPhone X encode h264 video c->ref always 7. what happened there, how could I specific reference frame number.

  


• ffmpeg concat skips frames near end of each subclip

  3 janvier 2024, par calvinusesyourcode

  So I have some video files to concat but in the resulting video the last few frames of each subclip are buggy. Imagine in the last 5 frames the first 3 frames are skipped and so at the end of each clip it seems to jitter.

  


  It should be virtually impossible for my input videos to have any differences between them, as they were all recorded on the same iPhone and all converted with the same command :

  


  command = [
            'ffmpeg', '-y',
            '-i', input_path,
            '-vf', 'scale=1080:1920',
            '-r', '30',
            '-c:v', 'libx264',
            output_path
        ]
subprocess.run(command, check=True)


  


  I have tried re-encoding instead of merely copying and adding -r 30 but that doesn't seem to work.

  


  subprocess.run(["ffmpeg", "-y", "-f", "concat", "-safe", "0", "-i", temp_textfile, "-c", "copy", output_path])


  


      subprocess.run(["ffmpeg", "-y", "-f", "concat", "-safe", "0", "-i", temp_textfile, "-r", "30", "-c:v", "libx264", "-c:a", "aac", output_path], check=True)


  


  Somewhere someone said to open in VLC and do a frame-by-frame, reporting that "the frames are actually there, just not visually when watching normally". In my case the frame-by-frame reveals the frames are indeed being skipped.

  


  Full console output :

  


  ffmpeg version 2023-05-18-git-01d9a84ef5-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa 
--enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58.  7.100 / 58.  7.100
  libavcodec     60. 14.100 / 60. 14.100
  libavformat    60.  5.100 / 60.  5.100
  libavdevice    60.  2.100 / 60.  2.100
  libavfilter     9.  8.100 /  9.  8.100
  libswscale      7.  2.100 /  7.  2.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d60610ebc0] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'run\broll_subclips.txt':
  Duration: N/A, start: -0.023220, bitrate: 3094 kb/s
  Stream #0:0(und): Video: h264 (High 10) (avc1 / 0x31637661), yuv420p10le(tv, bt2020nc/bt2020/arib-std-b67, progressive), 1080x1920, 2968 kb/s, 30 fps, 30 tbr, 15360 tbn
    Metadata:
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.14.100 libx264
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 126 kb/s
    Metadata:
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 000001d6066fd380] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX 
FMA3 BMI2 AVX2
[libx264 @ 000001d6066fd380] profile High 10, level 4.0, 4:2:0, 10-bit
[libx264 @ 000001d6066fd380] 264 - core 164 r3107 a8b68eb - H.264/MPEG-4 AVC codec - Copyleft 2003-2023 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=81 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'joined_clips.mp4':
  Metadata:
    encoder         : Lavf60.5.100
  Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p10le(tv, bt2020nc/bt2020/arib-std-b67, progressive), 1080x1920, q=2-31, 30 fps, 15360 tbn
    Metadata:
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.14.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.14.100 aac
frame=    0 fps=0.0 q=0.0 size=       0kB time=00:00:00.23 bitrate=   1.7kbits/s dup[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=    0 fps=0.0 q=0.0 size=       0kB time=00:00:01.97 bitrate=   0.2kbits/s dupframe=   42 fps= 41 q=41.0 size=     256kB time=00:00:01.97 bitrate=1062.7kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=   81 fps= 53 q=41.0 size=     768kB time=00:00:04.71 bitrate=1334.8kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  124 fps= 61 q=41.0 size=    1280kB time=00:00:06.10 bitrate=1717.1kbits/s duframe=  178 fps= 69 q=38.0 size=    1536kB time=00:00:07.96 bitrate=1579.9kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  235 fps= 76 q=41.0 size=    2048kB time=00:00:09.84 bitrate=1704.1kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  273 fps= 76 q=41.0 size=    2560kB time=00:00:11.12 bitrate=1885.5kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  309 fps= 75 q=41.0 size=    2816kB time=00:00:12.30 bitrate=1874.5kbits/s duframe=  354 fps= 77 q=41.0 size=    3328kB time=00:00:13.83 bitrate=1969.9kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  411 fps= 80 q=41.0 size=    3840kB time=00:00:15.72 bitrate=2001.1kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  479 fps= 85 q=41.0 size=    4096kB time=00:00:17.99 bitrate=1864.6kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d608de8100] Auto-inserting h264_mp4toannexb bitstream filter
frame=  515 fps= 84 q=41.0 size=    4608kB time=00:00:19.20 bitrate=1965.7kbits/s duframe=  549 fps= 81 q=41.0 size=    4864kB time=00:00:20.31 bitrate=1961.1kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d60c3e8d40] Auto-inserting h264_mp4toannexb bitstream filter
frame=  600 fps= 83 q=41.0 size=    5632kB time=00:00:22.03 bitrate=2093.7kbits/s du[mov,mp4,m4a,3gp,3g2,mj2 @ 000001d60c3e8d40] Auto-inserting h264_mp4toannexb bitstream filter
frame=  648 fps= 83 q=41.0 size=    5888kB time=00:00:23.61 bitrate=2042.5kbits/s du[out#0/mp4 @ 000001d6061163c0] video:6385kB audio:335kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.377336%
frame=  724 fps= 86 q=-1.0 Lsize=    6746kB time=00:00:24.03 bitrate=2299.4kbits/s dup=6 drop=2 speed=2.86x
[libx264 @ 000001d6066fd380] frame I:12    Avg QP:26.96  size: 87427
[libx264 @ 000001d6066fd380] frame P:191   Avg QP:32.28  size: 15534
[libx264 @ 000001d6066fd380] frame B:521   Avg QP:35.40  size:  4840
[libx264 @ 000001d6066fd380] consecutive B-frames:  2.9%  2.8%  2.1% 92.3%
[libx264 @ 000001d6066fd380] mb I  I16..4: 21.0% 56.5% 22.5%
[libx264 @ 000001d6066fd380] mb P  I16..4:  1.9%  6.3%  1.0%  P16..4: 25.0%  4.5%  2.2%  0.0%  0.0%    skip:59.1%
[libx264 @ 000001d6066fd380] mb B  I16..4:  0.2%  0.7%  0.1%  B16..8: 24.4%  1.8%  0.2%  direct: 0.3%  skip:72.3%  L0:46.0% L1:50.7% BI: 3.3%
[libx264 @ 000001d6066fd380] 8x8 transform intra:64.9% inter:79.1%
[libx264 @ 000001d6066fd380] coded y,uvDC,uvAC intra: 42.4% 26.9% 3.0% inter: 3.7% 0.9% 0.0%
[libx264 @ 000001d6066fd380] i16 v,h,dc,p: 25% 28% 12% 35%
[libx264 @ 000001d6066fd380] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 23% 18% 23%  5%  6%  6% 
 6%  6%  6%
[libx264 @ 000001d6066fd380] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 27% 21% 19%  5%  6%  6% 
 7%  5%  5%
[libx264 @ 000001d6066fd380] i8c dc,h,v,p: 71% 13% 13%  4%
[libx264 @ 000001d6066fd380] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 000001d6066fd380] ref P L0: 68.7% 17.8% 13.4%
[libx264 @ 000001d6066fd380] ref B L0: 88.4%  9.1%  2.5%
[libx264 @ 000001d6066fd380] ref B L1: 96.9%  3.1%
[libx264 @ 000001d6066fd380] kb/s:2167.24
[aac @ 000001d606184b40] Qavg: 346.828


  


  UPDATE : I am thinking that the way I am converting my files from .mov to .mp4 is the problem. Please suggest the best way to convert from iPhone 4k 60fps .mov files to nice 1080p 30fps .mp4 files. I know I could just use handbrake but I am trying to be a man here xD. Perhaps handbrake has a View ffmpeg code for conversion.

  


  UPDATE 2 : re-encoding the videos before concat with -c:v libx264 fixes the problem... which seems weird because that is how they were originally encoded...

  


  def join_broll(video_paths, desired_length, clip_length=None, output_path="quick_clips.mp4", preserve_inputs=True):
    subclips = []
    total_duration = 0

    temp_textfile = os.path.join(run_folder, "broll_subclips.txt")
    j = 0
    with open(temp_textfile, "w") as file:
        while True:
            for i, video_path in enumerate(video_paths):

                time_left = desired_length - total_duration
                video_duration = duration_of(video_path)
                subclip_path = f"subclip_{i+j}.mp4"

                if (not clip_length and video_duration < time_left) or (clip_length and clip_length < time_left):

                    if clip_length:

                        subclips.append(subclip_path)
                        subprocess.run(["ffmpeg", "-y", "-i", video_path, "-t", str(clip_length), "-c:v", "libx264", subclip_path]) # added "-c:v libx264"
                        total_duration += clip_length
                        file.write(f"file '{os.path.join('..', subclip_path)}'\n")

                    else:
                    
                        subclips.append(subclip_path)
                        subprocess.run(["ffmpeg", "-y", "-i", video_path, "-c:v", "libx264", subclip_path]) # added "-c:v libx264"
                        total_duration += video_duration
                        file.write(f"file '{subclip_path}'\n")

                else:

                    subclips.append(subclip_path)
                    subprocess.run(["ffmpeg", "-y", "-i", video_path, "-t", str(time_left), "-c:v", "libx264", subclip_path]) # added "-c:v libx264"
                    total_duration += time_left
                    file.write(f"file '{os.path.join('..', subclip_path)}'\n")

                    break

            j += 1
            if desired_length - total_duration < 0.1:
                break
                

    subprocess.run(["ffmpeg", "-y", "-f", "concat", "-safe", "0", "-i", temp_textfile, "-c", "copy", output_path])
    # subprocess.run(["ffmpeg", "-y", "-f", "concat", "-safe", "0", "-i", temp_textfile, "-r", "30", "-c:v", "libx264", "-c:a", "aac", output_path], check=True)
    return output_path