From 11cfc56bd0d1577b5b3ba6419f275dd23004e329 Mon Sep 17 00:00:00 2001
From: Mark Qvist <mark@unsigned.io>
Date: Tue, 4 Jun 2024 02:56:23 +0200
Subject: [PATCH] Codec2 encode and decode

---
 sbapp/sideband/audioproc.py | 129 ++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)

diff --git a/sbapp/sideband/audioproc.py b/sbapp/sideband/audioproc.py
index e69de29..740bf30 100644
--- a/sbapp/sideband/audioproc.py
+++ b/sbapp/sideband/audioproc.py
@@ -0,0 +1,129 @@
+import os
+import io
+import math
+import time
+import struct
+import numpy as np
+import RNS
+import LXMF
+
+if RNS.vendor.platformutils.is_android():
+    import pyogg
+    from pydub import AudioSegment
+else:
+    import sbapp.pyogg as pyogg
+    from sbapp.pydub import AudioSegment
+
+codec2_modes = {
+    # LXMF.AM_CODEC2_450PWB: ???, # No bindings
+    # LXMF.AM_CODEC2_450: ???,    # No bindings
+    LXMF.AM_CODEC2_700C: 700,
+    LXMF.AM_CODEC2_1200: 1200,
+    LXMF.AM_CODEC2_1300: 1300,
+    LXMF.AM_CODEC2_1400: 1400,
+    LXMF.AM_CODEC2_1600: 1600,
+    LXMF.AM_CODEC2_2400: 2400,
+    LXMF.AM_CODEC2_3200: 3200,
+}
+
+def samples_from_ogg(file_path=None):
+    if file_path != None and os.path.isfile(file_path):
+        opus_file = pyogg.OpusFile(file_path)
+        audio = AudioSegment(
+            bytes(opus_file.as_array()),
+            frame_rate=opus_file.frequency,
+            sample_width=opus_file.bytes_per_sample, 
+            channels=opus_file.channels)
+
+        audio = audio.split_to_mono()[0]
+        audio = audio.apply_gain(-audio.max_dBFS)
+        audio = audio.set_frame_rate(8000)
+        audio = audio.set_sample_width(2)
+        
+        return audio.get_array_of_samples()
+
+def samples_to_ogg(samples=None, file_path=None):
+    if file_path != None and samples != None:
+        pcm_data = io.BytesIO(samples)
+        channels = 1; samples_per_second = 8000; bytes_per_sample = 2
+
+        opus_buffered_encoder = pyogg.OpusBufferedEncoder()
+        opus_buffered_encoder.set_application("audio")
+        opus_buffered_encoder.set_sampling_frequency(samples_per_second)
+        opus_buffered_encoder.set_channels(channels)
+        opus_buffered_encoder.set_frame_size(20) # milliseconds    
+        ogg_opus_writer = pyogg.OggOpusWriter(file_path, opus_buffered_encoder)
+
+        frame_duration = 0.1
+        frame_size = int(frame_duration * samples_per_second)
+        bytes_per_frame = frame_size*bytes_per_sample
+        
+        while True:
+            pcm = pcm_data.read(bytes_per_frame)
+            if len(pcm) == 0:
+                break
+            ogg_opus_writer.write(memoryview(bytearray(pcm)))
+
+        ogg_opus_writer.close()
+
+def samples_to_wav(samples=None, file_path=None):
+    if samples != None and file_path != None:
+        import wave
+        with wave.open(file_path, "wb") as wf:
+            wf.setnchannels(1)
+            wf.setsampwidth(2)
+            wf.setframerate(8000)
+            wf.writeframes(samples)
+        return True
+
+# Samples must be 8KHz, 16-bit, 1 channel
+def encode_codec2(samples, mode):
+    ap_start = time.time()
+    import pycodec2
+    if not mode in codec2_modes:
+        return None
+
+    c2 = pycodec2.Codec2(codec2_modes[mode])
+    SPF = c2.samples_per_frame()
+    PACKET_SIZE = SPF * 2 # 16-bit samples
+    STRUCT_FORMAT = '{}h'.format(SPF)
+    N_FRAMES = math.floor(len(samples)/SPF)
+    frames = np.array(samples[0:N_FRAMES*SPF], dtype=np.int16)
+    
+    encoded = b""
+    for pi in range(0, N_FRAMES):
+        pstart = pi*SPF
+        pend = (pi+1)*SPF
+        frame = frames[pstart:pend]
+        encoded_packet = c2.encode(frame)
+        encoded += encoded_packet
+
+    ap_duration = time.time() - ap_start
+    RNS.log("Codec2 encoding complete in "+RNS.prettytime(ap_duration)+", bytes out: "+str(len(encoded)), RNS.LOG_DEBUG)
+
+    return encoded
+
+def decode_codec2(encoded_bytes, mode):
+    ap_start = time.time()
+    import pycodec2
+    if not mode in codec2_modes:
+        return None
+
+    c2 = pycodec2.Codec2(codec2_modes[mode])
+    SPF = c2.samples_per_frame()
+    BPF = c2.bytes_per_frame()
+    STRUCT_FORMAT = '{}h'.format(SPF)
+    N_FRAMES = math.floor(len(encoded_bytes)/BPF)
+
+    decoded = b""
+    for pi in range(0, N_FRAMES):
+        pstart = pi*BPF
+        pend = (pi+1)*BPF
+        encoded_packet = encoded_bytes[pstart:pend]
+        decoded_frame = c2.decode(encoded_packet)
+        decoded += struct.pack(STRUCT_FORMAT, *decoded_frame)
+
+    ap_duration = time.time() - ap_start
+    RNS.log("Codec2 decoding complete in "+RNS.prettytime(ap_duration)+", samples out: "+str(len(decoded)), RNS.LOG_DEBUG)
+
+    return decoded
\ No newline at end of file