【PaddleSpeech No.6】补全合成系列中的脚本中参数缺失 (#4004)

* run.sh修改：为 synthesize 和 synthesize_e2e 添加 --stage 参数控制 vocoder 模型选择，REAMDE.md修改：补充 stage 参数说明，明确 vocoder 选择逻辑

* 添加run.sh中stage参数相关的注释

* HiFiGAN改为MultiBand MelGAN

* cmsc文件改回原位（No.15不修改），这里只对No.6做修改

examples/canton/tts3/README.md

@@ -37,6 +37,7 @@ Run the command below to
 3. train the model.
 4. synthesize wavs.
     - synthesize waveform from `metadata.jsonl`.
+    - `--stage` controls the vocoder model during synthesis (0 = pwgan, 1 = hifigan).
     - synthesize waveform from text file.
 ```bash
 ./run.sh

examples/canton/tts3/run.sh

@@ -28,13 +28,13 @@ if [ ${stage} -le 1 ] && [ ${stop_stage} -ge 1 ]; then
 fi
 
 if [ ${stage} -le 2 ] && [ ${stop_stage} -ge 2 ]; then
-    # synthesize, vocoder is pwgan by default
-    CUDA_VISIBLE_DEVICES=${gpus} ./local/synthesize.sh ${conf_path} ${train_output_path} ${ckpt_name} || exit -1
+    # synthesize, vocoder is pwgan by default stage 0, stage 1 will use hifigan as vocoder
+    CUDA_VISIBLE_DEVICES=${gpus} ./local/synthesize.sh --stage 0 ${conf_path} ${train_output_path} ${ckpt_name} || exit -1
 fi
 
 if [ ${stage} -le 3 ] && [ ${stop_stage} -ge 3 ]; then
-    # synthesize_e2e, vocoder is pwgan by default
-    CUDA_VISIBLE_DEVICES=${gpus} ./local/synthesize_e2e.sh ${conf_path} ${train_output_path} ${ckpt_name} || exit -1
+    # synthesize_e2e, vocoder is pwgan by default stage 0, stage 1 will use hifigan as vocoder
+    CUDA_VISIBLE_DEVICES=${gpus} ./local/synthesize_e2e.sh --stage 0 ${conf_path} ${train_output_path} ${ckpt_name} || exit -1
 fi
 
 if [ ${stage} -le 4 ] && [ ${stop_stage} -ge 4 ]; then