MIDI player tempo issues

[riban-bw]

Describe the bug There are some issues with the MIDI player's integration with Zynthian tempo.

• Whilst playing in loop mode the tempo may be adjusted
• Tempo is reset at loop point but displayed tempo is not updated
• Tempo cannot be set before playback begins, e.g. to slow to allow learning / practice
• The file's playback tempo is asserted when the file is played
• The tempo is not indicated before file plays
• Running sequences change playback speed when SMF starts

Setup:

• HARDWARE Raspberry Pi 4 Model B Rev 1.2 Audio: Z2 ADAC Display: Z2 Display Wiring: Z2_V3 I2C: MCP23017@0x20, MCP23017@0x21, ADS1115@0x48, ADS1115@0x49
• SYSTEM Raspbian GNU/Linux 10 (buster) Build Date: 2022-10-06 Memory: 21% (828M/3838M) SD Card: 49% (14G/29G) Temperature: 46.2ºC Overclock: Maximum USB Storage: 27% (64G/235G)
• MIDI Profile: default.sh Tuning: 440 Hz Receive Mode: Stage (Omni On) ZS3 Sub-SnapShots: On MIDI to Output: Off Master Channel: 16
• SOFTWARE zyncoder: staging-2210 (98c3df2) zynthian-ui: testing (20d257c) zynthian-sys: staging-2210 (b723fb3) zynthian-data: staging-2210 (3bbc39c) zynthian-webconf: staging-2210 (7df8271)

Additional context I suggest implementing the following workflow:

• Always display the tempo within the MIDI Recorder / Player page
• Indicate the tempo at which the file will start to playback
• If transport is rolling, use the transport tempo
  • Adjusting tempo will change the transport tempo and set the SMF start tempo
  • SMF file's start tempo is not used
• If transport is stopped, use the SMF file's start tempo
  • Adjusting tempo will change the transport tempo and set the SMF start tempo
  • Moving away without changing tempo will not change transport tempo
• When a tempo marker is reached during playback of a SMF the ratio of the SMF start tempo and transport tempo when started is used to scale change to transport tempo - this ensures tempo changes are relative to the SMF tempo markers. It should also fix unexpected tempo changes during looping

[riban-bw]

An option may be:

• Within the MIDI player view implement a controller that adjusts the playback ration, e.g. x2
• If transport is running and file is stopped this control shows the rate at which the file would start to playback, changing as you highlight each SMF file
• If transport is not running this control does not change between selecting files and defaults to 1x
• If file is playing the control adjusts transport tempo as a ration of the files start tempo and the transport't tempo when file started to play

This gives the user the useful info of how much faster or slower (as a fraction of file's original playback speed) that a file plays back. It separates sequence tempo and SMF playback speed (in the user's mind). It may prove simpler to implement the UI.

The range of the control may be awkward to choose or may want to be dynamic, e.g. a file that should start at 120bpm may want to play at x0.2 .. x3.5 but a different file might want a different range.

[jofemodo]

Is this solved?