Index: source/libvpx/examples/decode_with_partial_drops.txt |
=================================================================== |
--- source/libvpx/examples/decode_with_partial_drops.txt (revision 0) |
+++ source/libvpx/examples/decode_with_partial_drops.txt (revision 0) |
@@ -0,0 +1,238 @@ |
+@TEMPLATE decoder_tmpl.c |
+Decode With Partial Drops Example |
+========================= |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION |
+This is an example utility which drops a series of frames (or parts of frames), |
+as specified on the command line. This is useful for observing the error |
+recovery features of the codec. |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_INCLUDES |
+#include <time.h> |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_INCLUDES |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELPERS |
+struct parsed_header |
+{ |
+ char key_frame; |
+ int version; |
+ char show_frame; |
+ int first_part_size; |
+}; |
+ |
+int next_packet(struct parsed_header* hdr, int pos, int length, int mtu) |
+{ |
+ int size = 0; |
+ int remaining = length - pos; |
+ /* Uncompressed part is 3 bytes for P frames and 10 bytes for I frames */ |
+ int uncomp_part_size = (hdr->key_frame ? 10 : 3); |
+ /* number of bytes yet to send from header and the first partition */ |
+ int remainFirst = uncomp_part_size + hdr->first_part_size - pos; |
+ if (remainFirst > 0) |
+ { |
+ if (remainFirst <= mtu) |
+ { |
+ size = remainFirst; |
+ } |
+ else |
+ { |
+ size = mtu; |
+ } |
+ |
+ return size; |
+ } |
+ |
+ /* second partition; just slot it up according to MTU */ |
+ if (remaining <= mtu) |
+ { |
+ size = remaining; |
+ return size; |
+ } |
+ return mtu; |
+} |
+ |
+void throw_packets(unsigned char* frame, int* size, int loss_rate, |
+ int* thrown, int* kept) |
+{ |
+ unsigned char loss_frame[256*1024]; |
+ int pkg_size = 1; |
+ int pos = 0; |
+ int loss_pos = 0; |
+ struct parsed_header hdr; |
+ unsigned int tmp; |
+ int mtu = 1500; |
+ |
+ if (*size < 3) |
+ { |
+ return; |
+ } |
+ putc('|', stdout); |
+ /* parse uncompressed 3 bytes */ |
+ tmp = (frame[2] << 16) | (frame[1] << 8) | frame[0]; |
+ hdr.key_frame = !(tmp & 0x1); /* inverse logic */ |
+ hdr.version = (tmp >> 1) & 0x7; |
+ hdr.show_frame = (tmp >> 4) & 0x1; |
+ hdr.first_part_size = (tmp >> 5) & 0x7FFFF; |
+ |
+ /* don't drop key frames */ |
+ if (hdr.key_frame) |
+ { |
+ int i; |
+ *kept = *size/mtu + ((*size % mtu > 0) ? 1 : 0); /* approximate */ |
+ for (i=0; i < *kept; i++) |
+ putc('.', stdout); |
+ return; |
+ } |
+ |
+ while ((pkg_size = next_packet(&hdr, pos, *size, mtu)) > 0) |
+ { |
+ int loss_event = ((rand() + 1.0)/(RAND_MAX + 1.0) < loss_rate/100.0); |
+ if (*thrown == 0 && !loss_event) |
+ { |
+ memcpy(loss_frame + loss_pos, frame + pos, pkg_size); |
+ loss_pos += pkg_size; |
+ (*kept)++; |
+ putc('.', stdout); |
+ } |
+ else |
+ { |
+ (*thrown)++; |
+ putc('X', stdout); |
+ } |
+ pos += pkg_size; |
+ } |
+ memcpy(frame, loss_frame, loss_pos); |
+ memset(frame + loss_pos, 0, *size - loss_pos); |
+ *size = loss_pos; |
+} |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELPERS |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT |
+/* Initialize codec */ |
+flags = VPX_CODEC_USE_ERROR_CONCEALMENT; |
+res = vpx_codec_dec_init(&codec, interface, &dec_cfg, flags); |
+if(res) |
+ die_codec(&codec, "Failed to initialize decoder"); |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT |
+ |
+Usage |
+----- |
+This example adds a single argument to the `simple_decoder` example, |
+which specifies the range or pattern of frames to drop. The parameter is |
+parsed as follows: |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ USAGE |
+if(argc < 4 || argc > 6) |
+ die("Usage: %s <infile> <outfile> [-t <num threads>] <N-M|N/M|L,S>\n", |
+ argv[0]); |
+{ |
+ char *nptr; |
+ int arg_num = 3; |
+ if (argc == 6 && strncmp(argv[arg_num++], "-t", 2) == 0) |
+ dec_cfg.threads = strtol(argv[arg_num++], NULL, 0); |
+ n = strtol(argv[arg_num], &nptr, 0); |
+ mode = (*nptr == '\0' || *nptr == ',') ? 2 : (*nptr == '-') ? 1 : 0; |
+ |
+ m = strtol(nptr+1, NULL, 0); |
+ if((!n && !m) || (*nptr != '-' && *nptr != '/' && |
+ *nptr != '\0' && *nptr != ',')) |
+ die("Couldn't parse pattern %s\n", argv[3]); |
+} |
+seed = (m > 0) ? m : (unsigned int)time(NULL); |
+srand(seed);thrown_frame = 0; |
+printf("Seed: %u\n", seed); |
+printf("Threads: %d\n", dec_cfg.threads); |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ USAGE |
+ |
+ |
+Dropping A Range Of Frames |
+-------------------------- |
+To drop a range of frames, specify the starting frame and the ending |
+frame to drop, separated by a dash. The following command will drop |
+frames 5 through 10 (base 1). |
+ |
+ $ ./decode_with_partial_drops in.ivf out.i420 5-10 |
+ |
+ |
+Dropping A Pattern Of Frames |
+---------------------------- |
+To drop a pattern of frames, specify the number of frames to drop and |
+the number of frames after which to repeat the pattern, separated by |
+a forward-slash. The following command will drop 3 of 7 frames. |
+Specifically, it will decode 4 frames, then drop 3 frames, and then |
+repeat. |
+ |
+ $ ./decode_with_partial_drops in.ivf out.i420 3/7 |
+ |
+Dropping Random Parts Of Frames |
+------------------------------- |
+A third argument tuple is available to split the frame into 1500 bytes pieces |
+and randomly drop pieces rather than frames. The frame will be split at |
+partition boundaries where possible. The following example will seed the RNG |
+with the seed 123 and drop approximately 5% of the pieces. Pieces which |
+are depending on an already dropped piece will also be dropped. |
+ |
+ $ ./decode_with_partial_drops in.ivf out.i420 5,123 |
+ |
+ |
+Extra Variables |
+--------------- |
+This example maintains the pattern passed on the command line in the |
+`n`, `m`, and `is_range` variables: |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_VARS |
+int n, m, mode; |
+unsigned int seed; |
+int thrown=0, kept=0; |
+int thrown_frame=0, kept_frame=0; |
+vpx_codec_dec_cfg_t dec_cfg = {0}; |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ EXTRA_VARS |
+ |
+ |
+Making The Drop Decision |
+------------------------ |
+The example decides whether to drop the frame based on the current |
+frame number, immediately before decoding the frame. |
+ |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PRE_DECODE |
+/* Decide whether to throw parts of the frame or the whole frame |
+ depending on the drop mode */ |
+thrown_frame = 0; |
+kept_frame = 0; |
+switch (mode) |
+{ |
+case 0: |
+ if (m - (frame_cnt-1)%m <= n) |
+ { |
+ frame_sz = 0; |
+ } |
+ break; |
+case 1: |
+ if (frame_cnt >= n && frame_cnt <= m) |
+ { |
+ frame_sz = 0; |
+ } |
+ break; |
+case 2: |
+ throw_packets(frame, &frame_sz, n, &thrown_frame, &kept_frame); |
+ break; |
+default: break; |
+} |
+if (mode < 2) |
+{ |
+ if (frame_sz == 0) |
+ { |
+ putc('X', stdout); |
+ thrown_frame++; |
+ } |
+ else |
+ { |
+ putc('.', stdout); |
+ kept_frame++; |
+ } |
+} |
+thrown += thrown_frame; |
+kept += kept_frame; |
+fflush(stdout); |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PRE_DECODE |