ref: 8064583d2621a159b01508c1fd0017c4e7887938
dir: /examples/vp8_scalable_patterns.txt/
@TEMPLATE encoder_tmpl.c VP8 Scalable Frame Patterns =========================== ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION This is an example demonstrating how to control the VP8 encoder's reference frame selection and update mechanism for video applications that benefit from a scalable bitstream. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION Configuration ------------- Scalable frame patterns are most useful in an error resilient context, so error resiliency mode is enabled, as in the `error_resilient.c` example. In addition, we want to disable automatic keyframe selection, so we force an interval of 1000 frames. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ENC_SET_CFG2 /* Enable error resilient mode */ cfg.g_error_resilient = 1; cfg.g_lag_in_frames = 0; cfg.kf_mode = VPX_KF_FIXED; /* Disable automatic keyframe placement */ cfg.kf_min_dist = cfg.kf_max_dist = 1000; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ENC_SET_CFG2 This example uses the following frame pattern (L->last_frame, G->golden_frame, A->alt_ref_frame): * Frame 0 Intra, use none, update L&G&A * Frame 1 Inter, use LGA, update none * Frame 2 Inter, use LGA, update L * Frame 3 Inter, use LGA, update none * Frame 4 Inter, use GA, update L&G * Frame 5 Inter, use LGA, update none * Frame 6 Inter, use LGA, update L * Frame 7 Inter, use LGA, update none * Frame 8 Inter, use A, update L&G&A * Frame 9 Inter, use LGA, update none * Frame 10 Inter, use LGA, update L * Frame 11 Inter, use LGA, update none * Frame 12 Inter, use GA, update L&G * Frame 13 Inter, use LGA, update none * Frame 14 Inter, use LGA, update L * Frame 15 Inter, use LGA, update none * ...Repeats the pattern from frame 0 Change this variable to test the 3 decodable streams case. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TWOPASS_VARS int num_streams = 5; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TWOPASS_VARS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PER_FRAME_CFG flags = 0; if(num_streams == 5) { switch(frame_cnt % 16) { case 0: flags |= VPX_EFLAG_FORCE_KF; flags |= VP8_EFLAG_FORCE_GF; flags |= VP8_EFLAG_FORCE_ARF; break; case 1: case 3: case 5: case 7: case 9: case 11: case 13: case 15: flags |= VP8_EFLAG_NO_UPD_LAST; flags |= VP8_EFLAG_NO_UPD_GF; flags |= VP8_EFLAG_NO_UPD_ARF; break; case 2: case 6: case 10: case 14: break; case 4: flags |= VP8_EFLAG_NO_REF_LAST; flags |= VP8_EFLAG_FORCE_GF; break; case 8: flags |= VP8_EFLAG_NO_REF_LAST; flags |= VP8_EFLAG_NO_REF_GF; flags |= VP8_EFLAG_FORCE_GF; flags |= VP8_EFLAG_FORCE_ARF; break; case 12: flags |= VP8_EFLAG_NO_REF_LAST; flags |= VP8_EFLAG_FORCE_GF; break; } } else { switch(frame_cnt % 9) { case 0: if(frame_cnt==0) { flags |= VPX_EFLAG_FORCE_KF; } else { cfg.rc_max_quantizer = 26; cfg.rc_min_quantizer = 0; cfg.rc_target_bitrate = 300; flags |= VP8_EFLAG_NO_REF_LAST; flags |= VP8_EFLAG_NO_REF_ARF; } flags |= VP8_EFLAG_FORCE_GF; flags |= VP8_EFLAG_FORCE_ARF; break; case 1: case 2: case 4: case 5: case 7: case 8: cfg.rc_max_quantizer = 45; cfg.rc_min_quantizer = 0; cfg.rc_target_bitrate = 230; break; case 3: case 6: cfg.rc_max_quantizer = 45; cfg.rc_min_quantizer = 0; cfg.rc_target_bitrate = 215; flags |= VP8_EFLAG_NO_REF_LAST; flags |= VP8_EFLAG_FORCE_ARF; break; } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PER_FRAME_CFG Observing The Effects --------------------- Use the `decode_with_drops` example to decode with various dropped frame patterns. Good patterns to start with are 1/2, 3/4, 7/8, and 15/16 drops.