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🎥 Command line media player
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#include <stdlib.h>#include <assert.h>#include <string.h>#include "misc/ctype.h"#include "common/common.h"#include "common/msg.h"#include "options/options.h"#include "sd.h"
// Filter for removing subtitle additions for deaf or hard-of-hearing (SDH)// This is for English, but may in part work for others too.// The intention is that it can always be active so may not remove// all SDH parts.// It is for filtering ASS encoded subtitles
struct buffer { char *string; int length; int pos;};
static void init_buf(struct buffer *buf, int length){ buf->string = talloc_size(NULL, length); buf->pos = 0; buf->length = length;}
static inline int append(struct sd *sd, struct buffer *buf, char c){ if (buf->pos >= 0 && buf->pos < buf->length) { buf->string[buf->pos++] = c; } else { // ensure that terminating \0 is always written if (c == '\0') buf->string[buf->length - 1] = c; } return c;}
// copy ass override tags, if they exist att current position,// from source string to destination buffer stopping at first// character following last sequence of '{text}'//// Parameters:// rpp read pointer pointer to source string, updated on return// buf write buffer//// on return the read pointer is updated to the position after// the tags.static void copy_ass(struct sd *sd, char **rpp, struct buffer *buf){ char *rp = *rpp;
while (rp[0] == '{') { while (*rp) { char tmp = append(sd, buf, rp[0]); rp++; if (tmp == '}') break; } } *rpp = rp;
return;}
// check for speaker label, like MAN:// normal subtitles may include mixed case text with : after so// only upper case is accepted and lower case l which for some// looks like upper case I unless filter_harder - then// lower case is also acceptable//// Parameters:// rpp read pointer pointer to source string, updated on return// buf write buffer//// scan in source string and copy ass tags to destination string// skipping speaker label if it exists//// if no label was found read pointer and write position in buffer// will be unchanged// otherwise they point to next position after label and next write positionstatic void skip_speaker_label(struct sd *sd, char **rpp, struct buffer *buf){ int filter_harder = sd->opts->sub_filter_SDH_harder; char *rp = *rpp; int old_pos = buf->pos;
copy_ass(sd, &rp, buf); // copy any leading "- " if (rp[0] == '-') { append(sd, buf, rp[0]); rp++; } copy_ass(sd, &rp, buf); while (rp[0] == ' ') { append(sd, buf, rp[0]); rp++; copy_ass(sd, &rp, buf); } // skip past valid data searching for : while (*rp && rp[0] != ':') { if (rp[0] == '{') { copy_ass(sd, &rp, buf); } else if ((mp_isalpha(rp[0]) && (filter_harder || mp_isupper(rp[0]) || rp[0] == 'l')) || mp_isdigit(rp[0]) || rp[0] == ' ' || rp[0] == '\'' || (filter_harder && (rp[0] == '(' || rp[0] == ')')) || rp[0] == '#' || rp[0] == '.' || rp[0] == ',') { rp++; } else { buf->pos = old_pos; return; } } if (!*rp) { // : was not found buf->pos = old_pos; return; } rp++; // skip : copy_ass(sd, &rp, buf); if (!*rp) { // end of data } else if (rp[0] == '\\' && rp[1] == 'N') { // line end follows - skip it as line is empty rp += 2; } else if (rp[0] == ' ') { while (rp[0] == ' ') { rp++; } if (rp[0] == '\\' && rp[1] == 'N') { // line end follows - skip it as line is empty rp += 2; } } else { // non space follows - no speaker label buf->pos = old_pos; return; } *rpp = rp;
return;}
// check for bracketed text, like [SOUND]// and skip it while preserving ass tags// any characters are allowed, brackets are seldom used in normal text//// Parameters:// rpp read pointer pointer to source string, updated on return// buf write buffer//// scan in source string// the first character in source string must by the starting '['// and copy ass tags to destination string but// skipping bracketed text if it looks like SDH//// return true if bracketed text was removed.// if not valid SDH read pointer and write buffer position will be unchanged// otherwise they point to next position after text and next write positionstatic bool skip_bracketed(struct sd *sd, char **rpp, struct buffer *buf){ char *rp = *rpp; int old_pos = buf->pos;
rp++; // skip past '[' // skip past valid data searching for ] while (*rp && rp[0] != ']') { if (rp[0] == '{') { copy_ass(sd, &rp, buf); } else { rp++; } } if (!*rp) { // ] was not found buf->pos = old_pos; return false; } rp++; // skip ] // skip trailing spaces while (rp[0] == ' ') { rp++; } *rpp = rp;
return true;}
// check for paranthesed text, like (SOUND)// and skip it while preserving ass tags// normal subtitles may include mixed case text in parentheses so// only upper case is accepted and lower case l which for some// looks like upper case I but if requested harder filtering// both upper and lower case is accepted//// Parameters:// rpp read pointer pointer to source string, updated on return// buf write buffer//// scan in source string// the first character in source string must be the starting '('// and copy ass tags to destination string but// skipping paranthesed text if it looks like SDH//// return true if paranthesed text was removed.// if not valid SDH read pointer and write buffer position will be unchanged// otherwise they point to next position after text and next write positionstatic bool skip_parenthesed(struct sd *sd, char **rpp, struct buffer *buf){ int filter_harder = sd->opts->sub_filter_SDH_harder; char *rp = *rpp; int old_pos = buf->pos;
rp++; // skip past '(' // skip past valid data searching for ) bool only_digits = true; while (*rp && rp[0] != ')') { if (rp[0] == '{') { copy_ass(sd, &rp, buf); } else if ((mp_isalpha(rp[0]) && (filter_harder || mp_isupper(rp[0]) || rp[0] == 'l')) || mp_isdigit(rp[0]) || rp[0] == ' ' || rp[0] == '\'' || rp[0] == '#' || rp[0] == '.' || rp[0] == ',' || rp[0] == '-' || rp[0] == '"' || rp[0] == '\\') { if (!mp_isdigit(rp[0])) only_digits = false; rp++; } else { buf->pos = old_pos; return false; } } if (!*rp) { // ) was not found buf->pos = old_pos; return false; } if (only_digits) { // number within parentheses is probably not SDH buf->pos = old_pos; return false; } rp++; // skip ) // skip trailing spaces while (rp[0] == ' ') { rp++; } *rpp = rp;
return true;}
// remove leading hyphen and following spaces in write buffer//// Parameters:// start_pos start position i buffer// buf buffer to remove in//// when removing characters the following are moved back//static void remove_leading_hyphen_space(struct sd *sd, int start_pos, struct buffer *buf){ int old_pos = buf->pos; if (start_pos < 0 || start_pos >= old_pos) return; append(sd, buf, '\0'); // \0 terminate for reading
// move past leading ass tags while (buf->string[start_pos] == '{') { while (buf->string[start_pos] && buf->string[start_pos] != '}') { start_pos++; } if (buf->string[start_pos]) start_pos++; // skip past '}' }
// if there is not a leading '-' no removing will be done if (buf->string[start_pos] != '-') { buf->pos = old_pos; return; }
char *rp = &buf->string[start_pos]; // read from here buf->pos = start_pos; // start writing here rp++; // skip '-' copy_ass(sd, &rp, buf); while (rp[0] == ' ') { rp++; // skip ' ' copy_ass(sd, &rp, buf); } while (*rp) { // copy the rest append(sd, buf, rp[0]); rp++; }}
// Filter ASS formatted string for SDH//// Parameters:// format format line from ASS configuration// n_ignored number of comma to skip as preprocessing have removed them// data ASS line. null terminated string if length == 0// length length of ASS input if not null terminated, 0 otherwise//// Returns a talloc allocated string with filtered ASS data (may be the same// content as original if no SDH was found) which must be released// by caller using talloc_free.//// Returns NULL if filtering resulted in all of ASS data being removed so no// subtitle should be outputchar *filter_SDH(struct sd *sd, char *format, int n_ignored, char *data, int length){ if (!format) { MP_VERBOSE(sd, "SDH filtering not possible - format missing\n"); return length ? talloc_strndup(NULL, data, length) : talloc_strdup(NULL, data); }
// need null terminated string char *ass = length ? talloc_strndup(NULL, data, length) : data;
int comma = 0; // scan format line to find the number of the field where the text is for (char *c = format; *c; c++) { if (*c == ',') { comma++; if (strncasecmp(c + 1, "Text", 4) == 0) break; } } // if preprocessed line some fields are skipped comma -= n_ignored;
struct buffer writebuf; struct buffer *buf = &writebuf;
init_buf(buf, strlen(ass) + 1); // with room for terminating '\0'
char *rp = ass;
// locate text field in ASS line for (int k = 0; k < comma; k++) { while (*rp) { char tmp = append(sd, buf, rp[0]); rp++; if (tmp == ',') break; } } if (!*rp) { talloc_free(buf->string); MP_VERBOSE(sd, "SDH filtering not possible - cannot find text field\n"); return length ? ass : talloc_strdup(NULL, ass); }
bool contains_text = false; // true if non SDH text was found bool line_with_text = false; // if last line contained text int wp_line_start = buf->pos; // write pos to start of last line int wp_line_end = buf->pos; // write pos to end of previous line with text (\N)
// go through the lines in the text // they are separated by \N while (*rp) { line_with_text = false; wp_line_start = buf->pos;
// skip any speaker label skip_speaker_label(sd, &rp, buf);
// go through the rest of the line looking for SDH in () or [] while (*rp && !(rp[0] == '\\' && rp[1] == 'N')) { copy_ass(sd, &rp, buf); if (rp[0] == '[') { if (!skip_bracketed(sd, &rp, buf)) { append(sd, buf, rp[0]); rp++; line_with_text = true; } } else if (rp[0] == '(') { if (!skip_parenthesed(sd, &rp, buf)) { append(sd, buf, rp[0]); rp++; line_with_text = true; } } else if (*rp && rp[0] != '\\') { if (rp[0] > 32 && rp[0] < 127 && rp[0] != '-') line_with_text = true; append(sd, buf, rp[0]); rp++; } else if (rp[0] == '\\' && rp[1] != 'N') { append(sd, buf, rp[0]); rp++; } } // either end of data or ASS line end defined by separating \N if (*rp) { // ASS line end if (line_with_text) { contains_text = true; wp_line_end = buf->pos; append(sd, buf, rp[0]); // copy backslash append(sd, buf, rp[1]); // copy N rp += 2; // move read pointer past \N } else { // no text in line, remove leading hyphen and spaces remove_leading_hyphen_space(sd, wp_line_start, buf); // and join with next line rp += 2; // move read pointer past \N } } } // if no normal text i last line - remove last line // by moving write pointer to start of last line if (!line_with_text) { buf->pos = wp_line_end; } else { contains_text = true; } if (length) talloc_free(ass); if (contains_text) { // the ASS data contained normal text after filtering append(sd, buf, '\0'); // '\0' terminate return buf->string; } else { // all data removed by filtering talloc_free(buf->string); return NULL; }}