Why does this MP4 video not play on iOS?

Question

flyff1991 OP

Created Apr ’23

Replies 1

Boosts 1

Views 1.4k

Participants 2

Open with the document App, only the file name and file type will be displayed, and the general video can be played directly.

So, I switched to AVplayer to play this video with only sound but no picture.

mp4info:

File:
  major brand:      mp42
  minor version:    0
  compatible brand: mp42
  compatible brand: mp41
  fast start:       yes

Movie:
  duration:   18842880 (media timescale units)
  duration:   209365 (ms)
  time scale: 90000
  fragments:  no

Found 2 Tracks
Track 1:
  flags:        1 ENABLED
  id:           1
  type:         Video
  duration: 209320 ms
  language: eng
  media:
    sample count: 5233
    timescale:    25000
    duration:     5233000 (media timescale units)
    duration:     209320 (ms)
    bitrate (computed): 9592.363 Kbps
  display width:  1920.000000
  display height: 1080.000000
  frame rate (computed): 25.000
  Sample Description 0
    Coding:       avc1 (H.264)
    Codec String: avc1.640029
    AVC Profile:          100 (High)
    AVC Profile Compat:   0
    AVC Level:            41
    AVC NALU Length Size: 4
    AVC SPS: [67640029ac2ca501e0111f7350101014000003000400000300ca10]
    AVC PPS: [68e881135250]
    Width:       1920
    Height:      1080
    Depth:       24
Track 2:
  flags:        1 ENABLED
  id:           2
  type:         Audio
  duration: 209320 ms
  language: eng
  media:
    sample count: 9814
    timescale:    48000
    duration:     10049536 (media timescale units)
    duration:     209365 (ms)
    bitrate (computed): 317.376 Kbps
  Sample Description 0
    Coding:       mp4a (MPEG-4 Audio)
    Codec String: mp4a.40.2
    Stream Type: Audio
    Object Type: MPEG-4 Audio
    Max Bitrate: 407250
    Avg Bitrate: 317375
    Buffer Size: 1536
    MPEG-4 Audio Object Type: 2 (AAC Low Complexity)
    MPEG-4 Audio Decoder Config:
      Sampling Frequency: 48000
      Channels: 2
    Sample Rate: 48000
    Sample Size: 16
    Channels:    2

I used the video conversion tool to convert it to fit the iPhone：

File:
  major brand:      isom
  minor version:    200
  compatible brand: isom
  compatible brand: iso2
  compatible brand: avc1
  compatible brand: mp41
  fast start:       yes

Movie:
  duration:   209320 (media timescale units)
  duration:   209320 (ms)
  time scale: 1000
  fragments:  no

Found 2 Tracks
Track 1:
  flags:        3 ENABLED IN-MOVIE
  id:           1
  type:         Video
  duration: 209320 ms
  language: eng
  media:
    sample count: 5233
    timescale:    12800
    duration:     2679296 (media timescale units)
    duration:     209320 (ms)
    bitrate (computed): 11996.339 Kbps
  display width:  1920.000000
  display height: 1080.000000
  frame rate (computed): 25.000
  Sample Description 0
    Coding:       avc1 (H.264)
    Codec String: avc1.640033
    AVC Profile:          100 (High)
    AVC Profile Compat:   0
    AVC Level:            51
    AVC NALU Length Size: 4
    AVC SPS: [27640033ac1316c0780227e5c05a8080809818002ee0000bb82f7be0f8442370]
    AVC PPS: [28ee1f2c]
    Width:       1920
    Height:      1080
    Depth:       24
Track 2:
  flags:        3 ENABLED IN-MOVIE
  id:           2
  type:         Audio
  duration: 209320 ms
  language: eng
  media:
    sample count: 9812
    timescale:    48000
    duration:     10047360 (media timescale units)
    duration:     209320 (ms)
    bitrate (computed): 317.379 Kbps
  Sample Description 0
    Coding:       mp4a (MPEG-4 Audio)
    Codec String: mp4a.40.2
    Stream Type: Audio
    Object Type: MPEG-4 Audio
    Max Bitrate: 317379
    Avg Bitrate: 317379
    Buffer Size: 0
    MPEG-4 Audio Object Type: 2 (AAC Low Complexity)
    MPEG-4 Audio Decoder Config:
      Sampling Frequency: 48000
      Channels: 2
    Sample Rate: 48000
    Sample Size: 16
    Channels:    2

The AVC Level and bitrate both higher than the first video, but it plays normally。

So why can't the first video play?

I want to know which MP4 videos the iPhone can't play. Apple doesn't have specific specs, but says it supports MP4 and H.264

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Answer 1

Beshbashbosh OP

Aug ’23

@flyff1991 I have been trying to play an MP4 from remote resource and I get the same symptoms, audio, no video. If I take the url I used and past in safari, same issue. Other urls I have with MP4s as the resource work fine but I can't seem to find why sometimes they don't work.

Did you ever find an answer to this?

I inspected the stream in VLC (where it does work), and noticed these differences between a working and non working mp4

Slightly different buffer resolution (e.g. buffer resolution 1920x1090 v video resolution 1920x1080)
Decoded format: Planar 4:2:0 YUV
Color Space : ITU-R BT.601 Range

In the mp4's that work, the buffer and video resolution match, and it did not include the decoded format or color space field.

One thing I noticed in your logs above is differences in timescales

Movie:
  duration:   18842880 (media timescale units)
  duration:   209365 (ms)
  time scale: 90000

v

Movie:
  duration:   209320 (media timescale units)
  duration:   209320 (ms)
  time scale: 1000

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