VSE: Retime Tool misinterprets the length of image sequences #108160

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opened 2023-05-22 20:21:56 +02:00 by Julien Kaspar · 2 comments

Julien Kaspar commented

2023-05-22 20:21:56 +02:00

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System Information
Operating system: Linux-6.3.2-gentoo-x86_64-AMD_Ryzen_Threadripper_1950X_16-Core_Processor-with-glibc2.36 64 Bits, X11 UI
Graphics card: Quadro GP100/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 530.41.03

Blender Version
Broken: version: 4.0.0 Alpha, branch: HEAD (modified), commit date: 2023-05-21 14:00, hash: 8c6908eba578
Worked: (newest version of Blender that worked as expected)

Short description of error
When importing an image sequence into the sequencer and making the "Retime" tool active in the toolbar, it shows the speed percentage.
But it always misinterprets the last frame as the second to last frame, showing 92% speed as a result instead of 100%.

An imported video in comparisson is always by default on 100% speed.

Sidenote: The retiming handle is strangely always placed a bit offset behind the last frame of the strip (In this case even between frames)

Exact steps for others to reproduce the error

Import an image sequence
Use the Retime tool and select the strip

**System Information** Operating system: Linux-6.3.2-gentoo-x86_64-AMD_Ryzen_Threadripper_1950X_16-Core_Processor-with-glibc2.36 64 Bits, X11 UI Graphics card: Quadro GP100/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 530.41.03 **Blender Version** Broken: version: 4.0.0 Alpha, branch: HEAD (modified), commit date: 2023-05-21 14:00, hash: `8c6908eba578` Worked: (newest version of Blender that worked as expected) **Short description of error** When importing an image sequence into the sequencer and making the "Retime" tool active in the toolbar, it shows the speed percentage. But it always misinterprets the last frame as the second to last frame, showing 92% speed as a result instead of 100%. ![Screenshot_20230522_201628.png](/attachments/cb60275a-b4bd-4dd1-9815-c0af1caf7eeb) An imported video in comparisson is always by default on 100% speed. ![Screenshot_20230522_201625.png](/attachments/327a2903-2433-43a7-b5bb-9ce0b05b2936) Sidenote: The retiming handle is strangely always placed a bit offset behind the last frame of the strip (In this case even between frames) **Exact steps for others to reproduce the error** - Import an image sequence - Use the Retime tool and select the strip

Screenshot_20230522_201625.png

31 KiB

Screenshot_20230522_201628.png

30 KiB

Julien Kaspar added the

labels 2023-05-22 20:21:56 +02:00

Richard Antalik added

Video Sequencer

and removed

labels 2023-05-25 06:49:12 +02:00

Evan Wilson changed title from ~~VSE: Retime Tool misinterprets the length of iamge sequences~~ to VSE: Retime Tool misinterprets the length of image sequences

2023-05-26 06:24:54 +02:00

Jonah Janzen commented

2023-08-04 02:44:36 +02:00

I'd like to try and tackle this issue, if no one else is already working on it!

I'd like to try and tackle this issue, if no one else is already working on it!

Jonah Janzen commented

2023-08-11 00:32:09 +02:00

It seems like the root cause of this issue also applies to videos, but they have so many frames in comparison to image sequences that the retime percentage just rounds up to 100% when dealing with them.
The retiming handle speed is determined in this function (strip_retiming.cc):

float SEQ_retiming_handle_speed_get(const Sequence *seq, const SeqRetimingHandle *handle)
{
  if (handle->strip_frame_index == 0) {
    return 1.0f;
  }

  const SeqRetimingHandle *handle_prev = handle - 1;

  const int frame_index_max = seq->len - 1;
  const int frame_retimed_prev = round_fl_to_int(handle_prev->retiming_factor * frame_index_max);
  const int frame_index_prev = handle_prev->strip_frame_index;
  const int frame_retimed = round_fl_to_int(handle->retiming_factor * frame_index_max);
  const int frame_index = handle->strip_frame_index;

  const int fragment_length_retimed = frame_retimed - frame_retimed_prev;
  const int fragment_length_original = frame_index - frame_index_prev;

  const float speed = float(fragment_length_retimed) / float(fragment_length_original);
  return speed;
}

So, there has to be an off-by-one error either here with frame_index_max, or elsewhere in the system when determining retiming sequence lengths. This is my first contribution to Blender, so I would appreciate it if someone more experienced could point me in the correct direction from here.

It seems like the root cause of this issue also applies to videos, but they have so many frames in comparison to image sequences that the retime percentage just rounds up to 100% when dealing with them. The retiming handle speed is determined in this function (strip_retiming.cc): ```cpp float SEQ_retiming_handle_speed_get(const Sequence *seq, const SeqRetimingHandle *handle) { if (handle->strip_frame_index == 0) { return 1.0f; } const SeqRetimingHandle *handle_prev = handle - 1; const int frame_index_max = seq->len - 1; const int frame_retimed_prev = round_fl_to_int(handle_prev->retiming_factor * frame_index_max); const int frame_index_prev = handle_prev->strip_frame_index; const int frame_retimed = round_fl_to_int(handle->retiming_factor * frame_index_max); const int frame_index = handle->strip_frame_index; const int fragment_length_retimed = frame_retimed - frame_retimed_prev; const int fragment_length_original = frame_index - frame_index_prev; const float speed = float(fragment_length_retimed) / float(fragment_length_original); return speed; } ``` So, there has to be an off-by-one error either here with `frame_index_max`, or elsewhere in the system when determining retiming sequence lengths. This is my first contribution to Blender, so I would appreciate it if someone more experienced could point me in the correct direction from here.

Jonah Janzen referenced a pull request that will close this issue

2023-08-19 22:47:28 +02:00

WIP: Fix retiming tool strip length misinterpretation #111307

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