shaka-packager/packager/media/base/muxer_util.cc

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// Copyright 2014 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "packager/media/base/muxer_util.h"
#include <inttypes.h>
#include <string>
#include <vector>
#include "packager/base/logging.h"
#include "packager/base/strings/string_number_conversions.h"
#include "packager/base/strings/string_split.h"
#include "packager/base/strings/stringprintf.h"
#include "packager/media/base/video_stream_info.h"
namespace shaka {
namespace {
Status ValidateFormatTag(const std::string& format_tag) {
if (format_tag.empty()) {
return Status(error::INVALID_ARGUMENT, "Format tag should not be empty");
}
// Format tag should follow this prototype: %0[width]d.
if (format_tag.size() > 3 && format_tag[0] == '%' && format_tag[1] == '0' &&
format_tag[format_tag.size() - 1] == 'd') {
unsigned out;
if (base::StringToUint(format_tag.substr(2, format_tag.size() - 3), &out)) {
return Status::OK;
}
}
return Status(
error::INVALID_ARGUMENT,
"Format tag should follow this prototype: %0[width]d if exist.");
}
} // namespace
namespace media {
Status ValidateSegmentTemplate(const std::string& segment_template) {
if (segment_template.empty()) {
return Status(error::INVALID_ARGUMENT,
"Segment template should not be empty.");
}
std::vector<std::string> splits = base::SplitString(
segment_template, "$", base::KEEP_WHITESPACE, base::SPLIT_WANT_ALL);
// ISO/IEC 23009-1:2012 5.3.9.4.4 Template-based Segment URL construction.
// Allowed identifiers: $$, $RepresentationID$, $Number$, $Bandwidth$, $Time$.
// "$" always appears in pairs, so there should be odd number of splits.
if (splits.size() % 2 == 0) {
return Status(error::INVALID_ARGUMENT,
"In segment templates, '$' should appear in pairs.");
}
bool has_number = false;
bool has_time = false;
// Every second substring in split output should be an identifier.
for (size_t i = 1; i < splits.size(); i += 2) {
// Each identifier may be suffixed, within the enclosing $ characters,
// with an additional format tag aligned with the printf format tag as
// defined in IEEE 1003.1-2008 [10] following this prototype: %0[width]d.
size_t format_pos = splits[i].find('%');
std::string identifier = splits[i].substr(0, format_pos);
if (format_pos != std::string::npos) {
Status tag_check = ValidateFormatTag(splits[i].substr(format_pos));
if (!tag_check.ok()) {
return tag_check;
}
}
// TODO(kqyang): Support "RepresentationID".
if (identifier == "RepresentationID") {
return Status(
error::UNIMPLEMENTED,
"Segment template flag $RepresentationID$ is not supported yet.");
} else if (identifier == "Number") {
has_number = true;
} else if (identifier == "Time") {
has_time = true;
} else if (identifier == "") {
if (format_pos != std::string::npos) {
return Status(error::INVALID_ARGUMENT,
"'$$' should not have any format tags.");
}
} else if (identifier != "Bandwidth") {
return Status(error::INVALID_ARGUMENT,
"'$" + splits[i] + "$' is not a valid identifier.");
}
}
if (has_number && has_time) {
return Status(
error::INVALID_ARGUMENT,
"In segment templates $Number$ and $Time$ should not co-exist.");
}
if (!has_number && !has_time) {
return Status(error::INVALID_ARGUMENT,
"In segment templates $Number$ or $Time$ should exist.");
}
// Note: The below check is skipped.
// Strings outside identifiers shall only contain characters that are
// permitted within URLs according to RFC 1738.
return Status::OK;
}
std::string GetSegmentName(const std::string& segment_template,
uint64_t segment_start_time,
uint32_t segment_index,
uint32_t bandwidth) {
DCHECK_EQ(Status::OK, ValidateSegmentTemplate(segment_template));
std::vector<std::string> splits = base::SplitString(
segment_template, "$", base::KEEP_WHITESPACE, base::SPLIT_WANT_ALL);
// "$" always appears in pairs, so there should be odd number of splits.
DCHECK_EQ(1u, splits.size() % 2);
std::string segment_name;
for (size_t i = 0; i < splits.size(); ++i) {
// Every second substring in split output should be an identifier.
// Simply copy the non-identifier part.
if (i % 2 == 0) {
segment_name += splits[i];
continue;
}
if (splits[i].empty()) {
// "$$" is an escape sequence, replaced with a single "$".
segment_name += "$";
continue;
}
size_t format_pos = splits[i].find('%');
std::string identifier = splits[i].substr(0, format_pos);
DCHECK(identifier == "Number" || identifier == "Time" ||
identifier == "Bandwidth");
std::string format_tag;
if (format_pos != std::string::npos) {
format_tag = splits[i].substr(format_pos);
DCHECK_EQ(Status::OK, ValidateFormatTag(format_tag));
// Replace %d formatting to correctly format uint64_t.
format_tag = format_tag.substr(0, format_tag.size() - 1) + PRIu64;
} else {
// Default format tag "%01d", modified to format uint64_t correctly.
format_tag = "%01" PRIu64;
}
if (identifier == "Number") {
// SegmentNumber starts from 1.
segment_name += base::StringPrintf(
format_tag.c_str(), static_cast<uint64_t>(segment_index + 1));
} else if (identifier == "Time") {
segment_name +=
base::StringPrintf(format_tag.c_str(), segment_start_time);
} else if (identifier == "Bandwidth") {
segment_name += base::StringPrintf(format_tag.c_str(),
static_cast<uint64_t>(bandwidth));
}
}
return segment_name;
}
} // namespace media
} // namespace shaka