Safari sends excessive HTTP range requests during HTML5 MOV playback
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):
- 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.
- Then, Safari sends a very small range request like Range: bytes=0-1 to confirm it receives a 206 Partial Content response.
- 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.
- 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.
- What could be the reason Safari repeatedly makes these very small requests for certain files?
- 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
ffmpegto move themoov atomto the beginning of the file with-movflags faststartdoes 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": ""
}
}
}