Remove the interpolation buffer

docs/integration-guide.md

@@ -725,8 +725,7 @@ Configuration passed to `client.add_player()`.
 | `initial_static_delay_ms` | `uint16_t` | `0` | Initial value for the user-adjustable static delay in milliseconds. Overridden by the persisted value if a `SendspinPersistenceProvider` is set. |
 | `psram_stack` | `bool` | `false` | Allocate sync/decode task stack in PSRAM (ESP-IDF only) |
 | `priority` | `unsigned` | `18` | FreeRTOS priority for the sync/decode task (ESP-IDF only). The default value, `18`, is one above the default `httpd_priority` (`17`). If you customize priorities, keep this above `httpd_priority` so the HTTP server task cannot starve the decoder during the initial burst of encoded audio that fills the buffer at stream start. |
-| `interpolation_buffer_location` | `MemoryLocation` | `PREFER_EXTERNAL` | Memory placement preference for the interpolation transfer buffer. `PREFER_EXTERNAL` tries SPIRAM first and falls back to internal RAM; `PREFER_INTERNAL` does the reverse. ESP-IDF only; ignored on host. |
-| `decode_buffer_location` | `MemoryLocation` | `PREFER_EXTERNAL` | Memory placement preference for the decode transfer buffer. Same semantics as `interpolation_buffer_location`. ESP-IDF only; ignored on host. |
+| `decode_buffer_location` | `MemoryLocation` | `PREFER_EXTERNAL` | Memory placement preference for the decode transfer buffer. `PREFER_EXTERNAL` tries SPIRAM first and falls back to internal RAM; `PREFER_INTERNAL` does the reverse. ESP-IDF only; ignored on host. |
 
 Each entry in `audio_formats` is an `AudioSupportedFormatObject`:
 
@@ -916,4 +915,4 @@ Set with `SendspinClient::set_log_level()`. Only affects host builds; ESP-IDF bu
 | `PREFER_EXTERNAL` | Prefer SPIRAM, fall back to internal RAM (ESP-IDF only) |
 | `PREFER_INTERNAL` | Prefer internal RAM, fall back to SPIRAM (ESP-IDF only) |
 
-Used by `SendspinClientConfig::websocket_payload_location` to control where the per-connection WebSocket payload reassembly buffer is allocated, and by `PlayerRoleConfig::interpolation_buffer_location` and `decode_buffer_location` to control where the player's transfer buffers are allocated. Ignored on host platforms (no internal/external distinction).
+Used by `SendspinClientConfig::websocket_payload_location` to control where the per-connection WebSocket payload reassembly buffer is allocated, and by `PlayerRoleConfig::decode_buffer_location` to control where the player's decode transfer buffer is allocated. Ignored on host platforms (no internal/external distinction).

docs/internals.md

@@ -335,7 +335,7 @@ Where `decoded_timestamp` is the server timestamp converted to client time (via
 |-------------|--------|
 | > +5000 us (or +500 us settling) | **Hard sync ahead**: insert silence frames to fill the gap |
 | < -5000 us (or -500 us settling) | **Hard sync behind**: drop the decoded chunk |
-| +100 to +5000 us | **Soft sync**: insert one interpolated frame (average of first two) |
+| +100 to +5000 us | **Soft sync**: insert one interpolated frame near the end (average of last two) |
 | -100 to -5000 us | **Soft sync**: remove last frame (blend into second-to-last) |
 | -100 to +100 us | **Dead zone**: pass audio through unmodified |
 

include/sendspin/config.h

@@ -119,10 +119,6 @@ struct PlayerRoleConfig {
     unsigned priority{DEFAULT_SYNC_TASK_PRIORITY};  ///< FreeRTOS priority for the sync/decode
                                                     ///< task (ESP-IDF only)
 
-    /// @brief Memory placement for the interpolation transfer buffer (ESP-IDF only; ignored on
-    /// host). Defaults to PREFER_EXTERNAL (SPIRAM).
-    MemoryLocation interpolation_buffer_location{MemoryLocation::PREFER_EXTERNAL};
-
     /// @brief Memory placement for the decode transfer buffer (ESP-IDF only; ignored on host).
     /// Defaults to PREFER_EXTERNAL (SPIRAM).
     MemoryLocation decode_buffer_location{MemoryLocation::PREFER_EXTERNAL};